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Infertility has been primarily treated as a female predicament but around one-half of infertility cases can be tracked to male factors. Clinically, male infertility is typically determined using measures of semen quality recommended by World Health Organization (WHO). A major limitation, however, is that standard semen analyses are relatively poor predictors of reproductive capacity and success. Despite major advances in understanding the molecular and cellular functions in sperm over the last several decades, semen analyses remain the primary method to assess male fecundity and fertility.
Chronological age is a significant determinant of human fecundity and fertility. The disease burden of infertility is likely to continue to rise as parental age at the time of conception has been steadily increasing. While the emphasis has been on the effects of advanced maternal age on adverse reproductive and offspring health, new evidence suggests that, irrespective of maternal age, higher male age contributes to longer time-to-conception, poor pregnancy outcomes and adverse health of the offspring in later life. The effect of chronological age on the genomic landscape of DNA methylation is profound and likely occurs through the accumulation of maintenance errors of DNA methylation over the lifespan, which have been originally described as epigenetic drift.
In recent years, the strong relation between age and DNA methylation profiles has enabled the development of statistical models to estimate biological age in most somatic tissue via different epigenetic ‘clock’ metrics, such as DNA methylation age and epigenetic age acceleration, which describe the degree to which predicted biological age deviates from chronological age. In turn, these epigenetic clock metrics have emerged as novel biomarkers of a host of phenotypes such as allergy and asthma in children, early menopause, increased incidence of cancer types and cardiovascular-related diseases, frailty and cognitive decline in adults. They also display good predictive ability for cancer, cardiovascular and all-cause mortality.
Epigenetic clock metrics are powerful tools to better understand the aging process in somatic tissue as well as their associations with adverse disease outcomes and mortality. Only a few studies have constructed epigenetic clocks specific to male germ cells and only one study reported that smokers trended toward an increased epigenetic age compared to non-smokers. These results indicate that sperm epigenetic clocks hold promise as a novel biomarker for reproductive health and/or environmental exposures. However, the relation between sperm epigenetic clocks and reproductive outcomes has not been examined.
There is a critical need for new measures of male fecundity for assessing overall reproductive success among couples in the general population. Data shows that sperm epigenetic clocks may fulfill this need as a novel biomarker that predicts pregnancy success among couples not seeking fertility treatment. Such a summary measure of sperm biological age is of clinical importance as it allows couples in the general population to realize their probability of achieving pregnancy during natural intercourse, thereby informing and expediting potential infertility treatment decisions. With the ability to customize high throughput DNA methylation arrays and capture sequencing approaches, the integration of the epigenetic clocks as part of standard clinical care can enhance our understanding of idiopathic infertility and the paternal contribution to reproductive success and offspring health.
The recent publication in Nature Medicine on genetic risk prediction in pre-implementation embryos(1) has already engendered heated discussion.(2,3) Kumar et al.(1) advocate the integration of polygenic risk scores (PRS) derived from pre-implantation genetic testing (PGT) with standard monogenic prediction. The paper focuses primarily on BRCA1 (and breast cancer) and APC (and colon cancer). Genetic tests for inherited disorders such as Tay-Sachs disease and breast cancers caused by BRCA1 and BRCA2 have been approved, but these are potentially devastating conditions with relatively simple inheritance; in most counseling situations the risks are straightforward to calculate.
The limitation on the amount and quality of DNA available from early embryo biopsies has made it difficult to produce genomic profiles of embryos in the IVF situation. Kumar et al. genotyped more than one-hundred embryos at hundreds of thousands of nucleotide sites and combined these genotype data with whole genome sequences of the prospective parents to produce reconstructed embryo genomes. These genomes were compared with those of ten born siblings and polygenic risk scores (PRS) were calculated for twelve conditions related to diseases. The PRS were claimed to be 97–99 percent accurate.
The primary market for this procedure would be couples seeking IVF, and Kumar and his colleagues, most of whom are employees of biotech companies, show that it is feasible to calculate a PRS for an embryo. The authors do present several caveats for the use of their procedure for PGT. For example, if a couple has a family history of a disease, they “may unintentionally prioritize” a mutant embryo for PGT-based only on PRS. They also acknowledge that results from research cohorts may not generalize to sibling embryos in IVF, which could limit the clinical utility of their approach. Kumar et al. also acknowledge the “portability” problem, namely PRSs have limited predictive accuracy in people with non-European ancestry(2,3) or of different ages or socioeconomic status.(4,5) They also mention the issue of unequal access to IVF technology in general.(2)
It is also important, However, to stress the limited predictive utility of PRS for common traits, not only diseases. There is increasing use of PRS among social scientists for characteristics such as years of education, which have heritabilities in the 10–15 percent range. Such studies, and potentially this one by Kumar et al., can lead to reduced emphasis on environmental and social associations with diseases or other traits. For omnigenic traits, such as height or body mass index (BMI), that have hundreds or thousands of associated nucleotide polymorphisms, and high heritability, the public might receive the mistaken impression that PGT or other genomic interventions can allow parents to choose their offspring’s phenotype.
For example, a recent study(6) of BMI in 881 subjects from Quebec found that PRS could explain only between 1.2 percent and 7.5 percent of the variance in BMI of these participants. Even when PRSs are statistically significant, their predictive value is too weak to be applied. The use of polygenic risk scores to select embryos, abbreviated ESPS for embryo selection based on polygenic scores, has been criticized before.(7) One of the important points raised by Turley et al.(7) concerns the environmental context of the children of IVG customers, which may be quite different from that of the sample of people from which the PRS was calculated. Because of gene-environment interactions, the predictive power of PRS for any complex trait is limited. As pointed out by Turley et al. (p. 79), “the predictive power of a polygenic score is maximized when the person is from the same environment as the research participants from whom the polygenic scores were derived. But this will never be the case in ESPS.”
PGT and ESPS raise ethical issues beyond IVG that more generally concern designer babies.(7,8) PRSs have been calculated for non-disease related traits such as educational attainment, income, or IQ, and it is conceivable that some prospective parents might regard these as important enough for intervention. There are also traits related to social constructs of race including skin pigmentation or facial features, and parental choice based on these phenotypes could enhance racial prejudices.
References
Kumar, A., K. Im, M. Banjevic, P.C. Ng, T. Tunstall, G. Garcia, L. Galhardo, J. Sun,O.N. Schaedel, B. Levy, D. Hongo, D. Kijacic, M. Kiehl, N.D. Tran, P.C. Klatsky, and M. Rabinowitz. 2022. Whole-genome risk prediction of common diseases in human preimplantation embryos. Nature Medicine28: 514–516. doi: 10.1038/s41591-022-01735-0.
Nature editorial. 2022. The alarming rise of complex genetic testing in human embryo testing. Nature603: 549–550. doi: 10.1038/d41586-022-00787-z.
Rosenberg, N., M. Edge, J. Pritchard, and M. Feldman. 2019. Interpreting polygenic scores, polygenic adaptation, and human phenotypic differences. Evol. Med. Public Health 2019: 26–34. doi: 10.1093/emph/eoy036.
Duncan, L.E., H. Shen, B. Gelaye, J. Meijsen, K.J. Ressler, M.W. Feldman, R.E. Peterson, and B.W. Domingue. 2019. Analysis of polygenic score usage and performance in diverse human populations. Nat. Comm. 10: 3328. doi: 10.1038/s41467-019-11112-0.
De Toro-Martin, J.E., F. Guenard, C. Bouchard, A. Tremblay, L. Perusse, and M.-C. Vohl. 2019. The challenge of stratifying obesity: attempts in the Quebec family study. Front. Genet. 10:994. doi: 10.3389/fgene.2019.00994.
Turley, P., M.N. Meyer, N. Wang, D. Cesarini, E. Hammonds, A.R. Martin, B.M. Neale, H.L. Rehm, L. Wilkins-Haug, D.J. Benjamin, S. Hyman, D. Laibson, and P.M. Visscher. 2021. Problems with using polygenic scores to select embryos. N. Engl. J. Med385(1): 78–86.
Forzano, F., O. Antonova, A. Clarke, G. de Wert, S. Hentze, Y. Jamshidi, Y. Moreau, M. Perola, I. Prokopenko, A. Read, A. Reymond, V. Stefansdottir, C. van El, and M. Genuardi. 2021. The use of polygenic risk scores in pre-implantation genetic testing: an unproven, unethical practice. European Journal of Human Genetics. doi: 10.1038/s41431-021-01000-x.
There has been much opinion, either as commentary in literature, meeting proceedings, or communiques from professional societies warning that this type of “high-impact” genetic information should not be given directly to the consumer as consumers will not fully understand the information presented to them, be unable to make proper risk-based decisions, results could cause panic and inappropriate action such as prophylactic oophorectomy or unwarranted risk-reduction mastectomy, or false reassurance in case of negative result and reduced future cancer screening measures taken by the consumer. However, there have been few studies to investigate these concerns.
The article by Kumar The alarming rise of complex genetic testing in human embryo selection
discusses the common trend of DTC (direct to consumer) and other genetic consutancy groups to offer disease risk assesment based on genetic predispostion genetic information in preimplantation embryos upon in vitro fertilization. Although this editorial discusses some caveats and potential ethical issues the opinion of this reviewer feels a certain number of key issues points have not been addressed (which will be discussed below) including:
the underlying risk of disclosure of all parties involved in decision making based on genetic testing including other family members
complicating ethical issues not addressed through proper guideline establishment and regulation as seen in countries that allow such advances to go without proper review board
a lack of discussion of the health disparities which may result of this type of genetic information or “selection” where groups of people would be shut out of such services due to socioeconomic status
Although the editorial highlights the issue that most genome wide association studies, on which most of the genetic counseling is based upon is from cohorts of European descent (and misses a large cohort which is Asian or African descent), there is little attention given to the issue that most panels of these agreed upon risk associated variants have not been validated in larger GWAS studies or that these panels only focus on the most common variants. An example of this would be BRCA1/2 and assumed future breast cancer risk.
PGS and PGT-A diagnoses have been built on biologically incorrect assumptions and on unvalidated guidelines dating back to 2016. These guidelines, which remain influential to this day, were published without a description of methods, without peer review, with no author identification, and without any references1 . The guidelines changed the binary diagnosis of euploid and aneuploid to normal, mosaic and aneuploid.
In fact most family risk assesment programs are more effective upon counseling of young women, not at the embryonic stage where genetic risk factors may not be evident or resulting from epigenetic changes or accumulated somatic mutation.
Lack of communication to all related and involved parties
Many times it is women, who having undergone these testings, have problems in communicating these risk findings to their children and family members, resulting in familial strains.
For instance, some women who discover they have the BRCA gene mutation, which puts them at higher risk for breast cancer, choose to tell their children about it before the children are old enough to understand the significance or deal with it, a new study found.
“Parents with the BRCA mutation are discussing their genetic test results with their offspring often many years before the offspring would need to do anything,” said study author Dr. Angela Bradbury, director of the Fox Chase Cancer Center’s Family Risk Assessment Program, in Philadelphia.
According to Bradbury, more than half of parents she surveyed told their children about genetic test results. Some parents reported that their children didn’t seem to understand the significance of the information, and some had initial negative reactions to the news.
“A lot of genetic information is being shared within families and there hasn’t been a lot of guidance from health-care professionals,” Bradbury said. “While this genetic risk may be shared accurately, there is risk of inaccurate sharing.”
In the study, Bradbury’s team interviewed 42 women who had the BRCA mutation. The researchers found that 55 percent of parents discussed the finding and the risk of breast cancer with at least one of their children who was under 25.
Also, most of the women didn’t avail themselves of the services of a doctor or genetic counselor in helping to tell their children, Bradbury’s group found.
The identification of familial risk factors can have very stressful impacts on the affected and their family however an IVF selection might even augment that familial stress. More research is needed on the psychological impact of such testing and a patient’s choice.
2. Lack of health disparity considerations in IVF selection research or guidelines
Another major concern, which has been highlighted in multiple articles on this site, is the growing health disparities between those who can obtain access to quality health care and those who are left out in the void of the medical system, either for economic or sociological reasons. This has been very apparent in the cancer treatment and personalized medicine world (for example the disparities of health care access for cancer treatment in the southern poorer rural parts of the US versus metropolitan areas and the gaping disparities seen between rich and poor countries in Africa). These health disparities have been also apparant in the genetic testing market, and although the DTC market meant to make genetic testing more affordable, interestingly these disparities still exist in this niche market.
3. Lack of proper establishment of Institutional Review Board oversight in countries allowing this technique have been problematic with regard to addressing bioethical concerns
The third concern is, of course, a bioethical concern on the use of advanced genetic technologies in the human and clinical setting. It has come to many people’s attention at the speed at which countries that do not seem to have strong bioethical review boards readily allow this type of research to be carried out without regulatory oversight or consequence. A prime example of this included the shunned Chinese research carried out to produce cloned humans, which was rapidly condemmed in the biomedical world however this research was conducted nonetheless. This lack of attention is addressed in Kumar’s article yet little guidance is given as to best practices to establish review boards overseeing such work and or research.
Parkinson’s Disease (PD), characterized by both motor and non-motor system pathology, is a common neurodegenerative disorder affecting about 1% of the population over age 60. Its prevalence presents an increasing social burden as the population ages. Since its introduction in the 1960’s, dopamine (DA)-replacement therapy (e.g., L-DOPA) has remained the gold standard treatment. While improving PD patients’ quality of life, the effects of treatment fade with disease progression and prolonged usage of these medications often (>80%) results in side effects including dyskinesias and motor fluctuations. Since the selective degeneration of A9 mDA neurons (mDANs) in the substantia nigra (SN) is a key pathological feature of the disease and is directly associated with the cardinal motor symptoms, dopaminergic cell transplantation has been proposed as a therapeutic strategy.
Researchers showed that mammalian fibroblasts can be converted into embryonic stem cell (ESC)-like induced pluripotent stem cells (iPSCs) by introducing four transcription factors i.e., Oct4, Sox2, Klf4, and c-Myc. This was then accomplished with human somatic cells, reprogramming them into human iPSCs (hiPSCs), offering the possibility of generating patient-specific stem cells. There are several major barriers to implementation of hiPSC-based cell therapy for PD. First, probably due to the limited understanding of the reprogramming process, wide variability exists between the differentiation potential of individual hiPSC lines. Second, the safety of hiPSC-based cell therapy has yet to be fully established. In particular, since any hiPSCs that remain undifferentiated or bear sub-clonal tumorigenic mutations have neoplastic potential, it is critical to eliminate completely such cells from a therapeutic product.
In the present study the researchers established human induced pluripotent stem cell (hiPSC)-based autologous cell therapy. Researchers reported a platform of core techniques for the production of mDA progenitors as a safe and effective therapeutic product. First, by combining metabolism-regulating microRNAs with reprogramming factors, a method was developed to more efficiently generate clinical grade iPSCs, as evidenced by genomic integrity and unbiased pluripotent potential. Second, a “spotting”-based in vitro differentiation methodology was established to generate functional and healthy mDA cells in a scalable manner. Third, a chemical method was developed that safely eliminates undifferentiated cells from the final product. Dopaminergic cells thus produced can express high levels of characteristic mDA markers, produce and secrete dopamine, and exhibit electrophysiological features typical of mDA cells. Transplantation of these cells into rodent models of PD robustly restored motor dysfunction and reinnervated host brain, while showing no evidence of tumor formation or redistribution of the implanted cells.
Together these results supported the promise of these techniques to provide clinically applicable personalized autologous cell therapy for PD. It was recognized by researchers that this methodology is likely to be more costly in dollars and manpower than techniques using off-the-shelf methods and allogenic cell lines. Nevertheless, the cost for autologous cell therapy may be expected to decrease steadily with technological refinement and automation. Given the significant advantages inherent in a cell source free of ethical concerns and with the potential to obviate the need for immunosuppression, with its attendant costs and dangers, it was proposed that this platform is suitable for the successful implementation of human personalized autologous cell therapy for PD.
scPopCorn: A New Computational Method for Subpopulation Detection and their Comparative Analysis Across Single-Cell Experiments
Reporter and Curator: Dr. Sudipta Saha, Ph.D.
4.2.5 scPopCorn: A New Computational Method for Subpopulation Detection and their Comparative Analysis Across Single-Cell Experiments, Volume 2 (Volume Two: Latest in Genomics Methodologies for Therapeutics: Gene Editing, NGS and BioInformatics, Simulations and the Genome Ontology), Part 4: Single Cell Genomics
Present day technological advances have facilitated unprecedented opportunities for studying biological systems at single-cell level resolution. For example, single-cell RNA sequencing (scRNA-seq) enables the measurement of transcriptomic information of thousands of individual cells in one experiment. Analyses of such data provide information that was not accessible using bulk sequencing, which can only assess average properties of cell populations. Single-cell measurements, however, can capture the heterogeneity of a population of cells. In particular, single-cell studies allow for the identification of novel cell types, states, and dynamics.
One of the most prominent uses of the scRNA-seq technology is the identification of subpopulations of cells present in a sample and comparing such subpopulations across samples. Such information is crucial for understanding the heterogeneity of cells in a sample and for comparative analysis of samples from different conditions, tissues, and species. A frequently used approach is to cluster every dataset separately, inspect marker genes for each cluster, and compare these clusters in an attempt to determine which cell types were shared between samples. This approach, however, relies on the existence of predefined or clearly identifiable marker genes and their consistent measurement across subpopulations.
Although the aligned data can then be clustered to reveal subpopulations and their correspondence, solving the subpopulation-mapping problem by performing global alignment first and clustering second overlooks the original information about subpopulations existing in each experiment. In contrast, an approach addressing this problem directly might represent a more suitable solution. So, keeping this in mind the researchers developed a computational method, single-cell subpopulations comparison (scPopCorn), that allows for comparative analysis of two or more single-cell populations.
The performance of scPopCorn was tested in three distinct settings. First, its potential was demonstrated in identifying and aligning subpopulations from single-cell data from human and mouse pancreatic single-cell data. Next, scPopCorn was applied to the task of aligning biological replicates of mouse kidney single-cell data. scPopCorn achieved the best performance over the previously published tools. Finally, it was applied to compare populations of cells from cancer and healthy brain tissues, revealing the relation of neoplastic cells to neural cells and astrocytes. Consequently, as a result of this integrative approach, scPopCorn provides a powerful tool for comparative analysis of single-cell populations.
This scPopCorn is basically a computational method for the identification of subpopulations of cells present within individual single-cell experiments and mapping of these subpopulations across these experiments. Different from other approaches, scPopCorn performs the tasks of population identification and mapping simultaneously by optimizing a function that combines both objectives. When applied to complex biological data, scPopCorn outperforms previous methods. However, it should be kept in mind that scPopCorn assumes the input single-cell data to consist of separable subpopulations and it is not designed to perform a comparative analysis of single cell trajectories datasets that do not fulfill this constraint.
Several innovations developed in this work contributed to the performance of scPopCorn. First, unifying the above-mentioned tasks into a single problem statement allowed for integrating the signal from different experiments while identifying subpopulations within each experiment. Such an incorporation aids the reduction of biological and experimental noise. The researchers believe that the ideas introduced in scPopCorn not only enabled the design of a highly accurate identification of subpopulations and mapping approach, but can also provide a stepping stone for other tools to interrogate the relationships between single cell experiments.
Researchers have embraced CRISPR gene-editing as a method for altering genomes, but some have reported that unwanted DNA changes may slip by undetected. The tool can cause large DNA deletions and rearrangements near its target site on the genome. Such alterations can confuse the interpretation of experimental results and could complicate efforts to design therapies based on CRISPR. The finding is in line with previous results from not only CRISPR but also other gene-editing systems.
CRISPR -Cas9 gene editing relies on the Cas9 enzyme to cut DNA at a particular target site. The cell then attempts to reseal this break using its DNA repair mechanisms. These mechanisms do not always work perfectly, and sometimes segments of DNA will be deleted or rearranged, or unrelated bits of DNA will become incorporated into the chromosome.
Researchers often use CRISPR to generate small deletions in the hope of knocking out a gene’s function. But when examining CRISPR edits, researchers found large deletions (often several thousand nucleotides) and complicated rearrangements of DNA sequences in which previously distant DNA sequences were stitched together. Many researchers use a method for amplifying short snippets of DNA to test whether their edits have been made properly. But this approach might miss larger deletions and rearrangements.
These deletions and rearrangements occur only with gene-editing techniques that rely on DNA cutting and not with some other types of CRISPR modifications that avoid cutting DNA. Such as a modified CRISPR system to switch one nucleotide for another without cutting DNA and other systems use inactivated Cas9 fused to other enzymes to turn genes on or off, or to target RNA. Overall, these unwanted edits are a problem that deserves more attention, but this should not stop anyone from using CRISPR. Only when people use it, they need to do a more thorough analysis about the outcome.
Biologists may have been building a more nuanced view of sex, but society has yet to catch up. True, more than half a century of activism from members of the lesbian, gay, bisexual and transgender community has softened social attitudes to sexual orientation and gender. Many societies are now comfortable with men and women crossing conventional societal boundaries in their choice of appearance, career and sexual partner. But when it comes to sex, there is still intense social pressure to conform to the binary model.
This pressure has meant that people born with clear DSDs (difference/disorder of sex development) often undergo surgery to ‘normalize’ their genitals. Such surgery is controversial because it is usually performed on babies, who are too young to consent, and risks assigning a sex at odds with the child’s ultimate gender identity — their sense of their own gender. Intersex advocacy groups have therefore argued that doctors and parents should at least wait until a child is old enough to communicate their gender identity, which typically manifests around the age of three, or old enough to decide whether they want surgery at all.
As many as 1 person in 100 has some form of “DSD” with or without external manifestation. Diagnoses of DSDs previously relied on hormone tests, anatomical inspections and imaging, followed by painstaking tests of one gene at a time. Now, advances in genetic techniques mean that teams can analyze multiple genes at once, aiming straight for a genetic diagnosis and making the process less stressful for families. Children with DSDs are treated by multidisciplinary teams that aim to tailor management and support to each individual and their family, but this usually involves raising a child as male or female even if no surgery is done.
The simple scenario that all learn is that two X chromosomes make someone female, and an X and a Y chromosome make someone male. These are simplistic ways of thinking about what is scientifically very complex. Anatomy, hormones, cells, and chromosomes (and also personal identity convictions) are actually not usually aligned with this binary classification.
More than 25 genes that affect sex development have now been identified, and they have a wide range of variations that affect people in subtle ways. Many differences aren’t even noticed until incidental medical encounters, such as a forty-six-year-old woman pregnant with her third child, found after amniocentesis that half her cells carry male chromosomes. Or a seventy-year-old father of three who learns during a hernia repair that he has a uterus.
Furthermore, scientists now understood that everyone’s body is made up of a patchwork of genetically distinct cells, some of which may have a different sex than the rest. This “mosaicism” can have effects ranging from undetectable to extraordinary, such as “identical” twins of different sexes. An extremely common instance of mosaicism comes from cells passing over the placental barrier during pregnancy. Men often carry female cells from their mothers, and women carry male cells from their sons. Research has shown that these cells remain present for decades, but what effects they have on disease and behavior is an essentially unstudied question.
Knowing the genetic vulnerability of bladder cancer for therapeutic intervention, Volume 2 (Volume Two: Latest in Genomics Methodologies for Therapeutics: Gene Editing, NGS and BioInformatics, Simulations and the Genome Ontology), Part 1: Next Generation Sequencing (NGS)
Knowing the genetic vulnerability of bladder cancer for therapeutic intervention
Reporter and Curator: Dr. Sudipta Saha, Ph.D.
A mutated gene called RAS gives rise to a signalling protein Ral which is involved in tumour growth in the bladder. Many researchers tried and failed to target and stop this wayward gene. Signalling proteins such as Ral usually shift between active and inactive states.
So, researchers next tried to stop Ral to get into active state. In inacvtive state Ral exposes a pocket which gets closed when active. After five years, the researchers found a small molecule dubbed BQU57 that can wedge itself into the pocket to prevent Ral from closing and becoming active. Now, BQU57 has been licensed for further development.
Researchers have a growing genetic data on bladder cancer, some of which threaten to overturn the supposed causes of bladder cancer. Genetics has also allowed bladder cancer to be reclassified from two categories into five distinct subtypes, each with different characteristics and weak spots. All these advances bode well for drug development and for improved diagnosis and prognosis.
Among the groups studying the genetics of bladder cancer are two large international teams: Uromol (named for urology and molecular biology), which is based at Aarhus University Hospital in Denmark, and The Cancer Genome Atlas (TCGA), based at institutions in Texas and Boston. Each team tackled a different type of cancer, based on the traditional classification of whether or not a tumour has grown into the muscle wall of the bladder. Uromol worked on the more common, earlier form, non-muscle-invasive bladder cancer, whereas TCGA is looking at muscle-invasive bladder cancer, which has a lower survival rate.
The Uromol team sought to identify people whose non-invasive tumours might return after treatment, becoming invasive or even metastatic. Bladder cancer has a high risk of recurrence, so people whose non-invasive cancer has been treated need to be monitored for many years, undergoing cystoscopy every few months. They looked for predictive genetic footprints in the transcriptome of the cancer, which contains all of a cell’s RNA and can tell researchers which genes are turned on or off.
They found three subgroups with distinct basal and luminal features, as proposed by other groups, each with different clinical outcomes in early-stage bladder cancer. These features sort bladder cancer into genetic categories that can help predict whether the cancer will return. The researchers also identified mutations that are linked to tumour progression. Mutations in the so-called APOBEC genes, which code for enzymes that modify RNA or DNA molecules. This effect could lead to cancer and cause it to be aggressive.
The second major research group, TCGA, led by the National Cancer Institute and the National Human Genome Research Institute, that involves thousands of researchers across USA. The project has already mapped genomic changes in 33 cancer types, including breast, skin and lung cancers. The TCGA researchers, who study muscle-invasive bladder cancer, have looked at tumours that were already identified as fast-growing and invasive.
The work by Uromol, TCGA and other labs has provided a clearer view of the genetic landscape of early- and late-stage bladder cancer. There are five subtypes for the muscle-invasive form: luminal, luminal–papillary, luminal–infiltrated, basal–squamous, and neuronal, each of which is genetically distinct and might require different therapeutic approaches.
Bladder cancer has the third-highest mutation rate of any cancer, behind only lung cancer and melanoma. The TCGA team has confirmed Uromol research showing that most bladder-cancer mutations occur in the APOBEC genes. It is not yet clear why APOBEC mutations are so common in bladder cancer, but studies of the mutations have yielded one startling implication. The APOBEC enzyme causes mutations early during the development of bladder cancer, and independent of cigarette smoke or other known exposures.
The TCGA researchers found a subset of bladder-cancer patients, those with the greatest number of APOBEC mutations, had an extremely high five-year survival rate of about 75%. Other patients with fewer APOBEC mutations fared less well which is pretty surprising.
This detailed knowledge of bladder-cancer genetics may help to pinpoint the specific vulnerabilities of cancer cells in different people. Over the past decade, Broad Institute researchers have identified more than 760 genes that cancer needs to grow and survive. Their genetic map might take another ten years to finish, but it will list every genetic vulnerability that can be exploited. The goal of cancer precision medicine is to take the patient’s tumour and decode the genetics, so the clinician can make a decision based on that information.
2.1.5.5 Promising research for a male birth control pill, Volume 2 (Volume Two: Latest in Genomics Methodologies for Therapeutics: Gene Editing, NGS and BioInformatics, Simulations and the Genome Ontology), Part 2: CRISPR for Gene Editing and DNA Repair
Scientists think excessive population growth is a cause of scarcity and environmental degradation. A male pill could reduce the number of unintended pregnancies, which accounts for 40 percent of all pregnancies worldwide.
But, big drug companies long ago dropped out of the search for a male contraceptive pill which is able to chemically intercept millions of sperm before they reach a woman’s egg. Right now the chemical burden for contraception relies solely on the female. There’s not much activity in the male contraception field because an effective solution is available on the female side.
Presently, male contraception means a condom or a vasectomy. But researchers from Center for Drug Discovery at Baylor College of Medicine, USA are renewing the search for a better option—an easy-to-take pill that’s safe, fast-acting, and reversible.
The scientists began with lists of genes active in the testes for sperm production and motility and then created knockout mice that lack those genes. Using the gene-editing technology called CRISPR, in collaboration with Japanese scientists, they have so far made more than 75 of these “knockout” mice.
They allowed these mice to mate with normal (wild type) female mice, and if their female partners don’t get pregnant after three to six months, it means the gene might be a target for a contraceptive. Out of 2300 genes that are particularly active in the testes of mice, the researchers have identified 30 genes whose deletion makes the male infertile. Next the scientists are planning a novel screening approach to test whether any of about two billion chemicals can disable these genes in a test tube. Promising chemicals could then be fed to male mice to see if they cause infertility.
Female birth control pills use hormones to inhibit a woman’s ovaries from releasing eggs. But hormones have side effects like weight gain, mood changes, and headaches. A trial of one male contraceptive hormone was stopped early in 2011 after one participant committed suicide and others reported depression. Moreover, some drug candidates have made animals permanently sterile which is not the goal of the research. The challenge is to prevent sperm being made without permanently sterilizing the individual.
As a better way to test drugs, Scientists at University of Georgia, USA are investigating yet another high-tech approach. They are turning human skin cells into stem cells that look and act like the spermatogonial cells in the testes. Testing drugs on such cells might provide more accurate leads than tests on mice.
The male pill would also have to start working quickly, a lot sooner than the female pill, which takes about a week to function. Scientists from University of Dundee, U.K. admitted that there are lots of challenges. Because, a women’s ovary usually release one mature egg each month, while a man makes millions of sperm every day. So, the male pill has to be made 100 percent effective and act instantaneously.
MicroRNAs (miRNAs) are a group of small non-coding RNA molecules that play a major role in posttranscriptional regulation of gene expression and are expressed in an organ-specific manner. One miRNA can potentially regulate the expression of several genes, depending on cell type and differentiation stage. They control every cellular process and their altered regulation is involved in human diseases. miRNAs are differentially expressed in the male and female gonads and have an organ-specific reproductive function. Exerting their affect through germ cells and gonadal somatic cells, miRNAs regulate key proteins necessary for gonad development. The role of miRNAs in the testes is only starting to emerge though they have been shown to be required for adequate spermatogenesis. In the ovary, miRNAs play a fundamental role in follicles’ assembly, growth, differentiation, and ovulation.
Deciphering the underlying causes of idiopathic male infertility is one of the main challenges in reproductive medicine. This is especially relevant in infertile patients displaying normal seminal parameters and no urogenital or genetic abnormalities. In these cases, the search for additional sperm biomarkers is of high interest. This study was aimed to determine the implications of the sperm miRNA expression profiles in the reproductive capacity of normozoospermic infertile individuals. The expression levels of 736 miRNAs were evaluated in spermatozoa from normozoospermic infertile males and normozoospermic fertile males analyzed under the same conditions. 57 miRNAs were differentially expressed between populations; 20 of them was regulated by a host gene promoter that in three cases comprised genes involved in fertility. The predicted targets of the differentially expressed miRNAs unveiled a significant enrichment of biological processes related to embryonic morphogenesis and chromatin modification. Normozoospermic infertile individuals exhibit a specific sperm miRNA expression profile clearly differentiated from normozoospermic fertile individuals. This miRNA cargo has potential implications in the individuals’ reproductive competence.
Circulating or “extracellular” miRNAs detected in biological fluids, could be used as potential diagnostic and prognostic biomarkers of several disease, such as cancer, gynecological and pregnancy disorders. However, their contributions in female infertility and in vitro fertilization (IVF) remain unknown. Polycystic ovary syndrome (PCOS) is a frequent endocrine disorder in women. PCOS is associated with altered features of androgen metabolism, increased insulin resistance and impaired fertility. Furthermore, PCOS, being a syndrome diagnosis, is heterogeneous and characterized by polycystic ovaries, chronic anovulation and evidence of hyperandrogenism, as well as being associated with chronic low-grade inflammation and an increased life time risk of type 2 diabetes. Altered miRNA levels have been associated with diabetes, insulin resistance, inflammation and various cancers. Studies have shown that circulating miRNAs are present in whole blood, serum, plasma and the follicular fluid of PCOS patients and that these might serve as potential biomarkers and a new approach for the diagnosis of PCOS. Presence of miRNA in mammalian follicular fluid has been demonstrated to be enclosed within microvesicles and exosomes or they can also be associated to protein complexes. The presence of microvesicles and exosomes carrying microRNAs in follicular fluid could represent an alternative mechanism of autocrine and paracrine communication inside the ovarian follicle. The investigation of the expression profiles of five circulating miRNAs (let-7b, miR-29a, miR-30a, miR-140 and miR-320a) in human follicular fluid from women with normal ovarian reserve and with polycystic ovary syndrome (PCOS) and their ability to predict IVF outcomes showed that these miRNAs could provide new helpful biomarkers to facilitate personalized medical care for oocyte quality in ART (Assisted Reproductive Treatment) and during IVF (In Vitro Fertilization).
2.1.5.12 Genomics Orientations for Personalized Medicine: Request for Book Review Writing on Amazon.com, Volume 2 (Volume Two: Latest in Genomics Methodologies for Therapeutics: Gene Editing, NGS and BioInformatics, Simulations and the Genome Ontology), Part 2: CRISPR for Gene Editing and DNA Repair
Recent Advances in Gene Editing Technology Adds New Therapeutic Potential for the Genomic Era: Medical Interpretation of the Genomics Frontier – CRISPR – Cas9
Introduction
21.1 Introducing CRISPR/Cas9 Gene Editing Technology – Works by Jennifer A. Doudna
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