Genetics in human reproduction

Abstract

Approximately 50% of the causes of infertility are of genetic origin. The objective of this study was to analyze the role of genetics in human reproduction by reviewing the main genetic causes of infertility and the use of preimplantation genetic testing in Brazil. This literature review comprised articles in English and Portuguese published on databases PubMed, Scielo, and Bireme from 1990 to 2019. Randomized clinical trials and specialized guidelines were given preference whenever possible. Genetic cause can be traced back to up to 20% of the cases of severe azoospermia or oligozoospermia. Subjects with these conditions are good candidates for genetic screening. In women, genetic causes of infertility (fragile X syndrome, X-trisomy, and Turner's syndrome, some of which diagnosed with karyotyping) culminate with premature ovarian failure. Genetic screening helps advise couples of the risk of experiencing early reproductive capacity loss and of the chances of their offspring carrying genetic disorders. In addition to enhancing the prevention of serious diseases in the offspring of couples at increased risk of genetic diseases, preimplantation genetic screening improves the success rates of assisted reproduction procedures by allowing the selection of euploid embryos for transfer. The interface between genetics and human reproduction has gained significant relevance, but discussions are still needed on which procedures are clinically and ethically acceptable and how they should be regulated.

“That’s Only for Women”: The Importance of Educating HIV-Positive Sexual Minority Men on HPV and High Resolution Anoscopy (HRA)

“…With this here, it’s different because I didn’t actually know there’s a thing called rectal cancer 11 ‘till my friend got it and passed from it. (FGD1)…”

“…Some participants discussed friends who had cancer, but they never "knew really what type of cancer," or had assumed that it was "a prostate thing." One participant discussed how he had first learned about rectal cancer by seeing a friend undergoing treatment for it: With this here, it's different because I didn't actually know there's a thing called rectal cancer 11 'till my friend got it and passed from it. (FGD1)…”

“…1,2 Concomitant with high rates of HIV/AIDS in these communities are similarly significant burdens of other sexually transmitted infections (STIs), including high rates of anogenital Human Papilloma Virus (HPV) infection, with associated anorectal, penile, and lower genital tract neoplasms. [3][4][5][6][7][8][9][10] While tremendous progress has been made in extending lifespan and reducing morbidity in persons living with HIV/AIDS, the phenomenon of HIV and HPV co-infection has led to increasing rates of anal intraepithelial neoplasia, 11 anal cancers, and rectal cancers in these groups. 10,[12][13][14][15][16][17] Despite advances in implementing highly active antiretroviral therapy (HAART) among persons living with HIV, reduction in incidences of these cancers has not been observed, and in fact have increased.…”

Whole exome sequencing identifies genes associated with non-obstructive azoospermia

“…Approximately 7% of male population worldwide suffer from infertility, 1 which is mainly caused by azoospermia, a condition with the highest frequency of known genetic factors contributing to male infertility (about 25%) 2 . Given that nearly 50% of infertility cases are associated with genetic defects, 3 the genetic etiology for azoospermia is still very elusive, the genetic basis of azoospermia in most cases remains unknown. In terms of pathobiological mechanism, azoospermia can be categorized into two groups: non-obstructive azoospermia which is defined as no sperm in the ejaculate due to failure of spermatogenesis, and obstructive azoospermia which is defined as the absence of spermatozoa in the ejaculate despite of the normal spermatogenesis.…”

Whole Exome Sequencing Identifies Genes Associated With Non-Obstructive Azoospermia

“…Approximately 7% of the male population worldwide suffer from infertility, and one of the main causes is azoospermia, which is a condition contributing to male infertility with the highest frequency of known genetic factors (about 25%) ( Krausz and Riera-Escamilla 2018 ; Rodrigues, Polisseni et al, 2020 ). Given that nearly 50% of azoospermia cases are estimated to be associated with genetic defects, the etiology of azoospermia is still very elusive ( Rodrigues, Polisseni et al, 2020 ).…”