Genetics of male infertility

The first wave of information from the analysis of the human genome revealed SNPs to be the main source of genetic and phenotypic human variation. However, the advent of genome-scanning technologies has now uncovered an unexpectedly large extent of what we term 'structural variation' in the human genome. This comprises microscopic and, more commonly, submicroscopic variants, which include deletions, duplications and large-scale copy-number variants - collectively termed copy-number variants or copy-number polymorphisms - as well as insertions, inversions and translocations. Rapidly accumulating evidence indicates that structural variants can comprise millions of nucleotides of heterogeneity within every genome, and are likely to make an important contribution to human diversity and disease susceptibility.

New data regarding the diagnosis and treatment of male infertility have emerged and led to an update of the European Association of Urology (EAU) guidelines for Male Infertility. To review the new EAU guidelines for Male Infertility. A comprehensive work-up of the literature obtained from Medline, the Cochrane Central Register of Systematic Reviews, and reference lists in publications and review articles was developed and screened by a group of urologists and andrologists appointed by the EAU Guidelines Committee. Previous recommendations based on the older literature on this subject were taken into account. Levels of evidence and grade of guideline recommendations were added, modified from the Oxford Centre for Evidence-based Medicine Levels of Evidence. These EAU guidelines are a short comprehensive overview of the updated guidelines of male infertility as recently published by the EAU (http://www.uroweb.org/guidelines/online-guidelines/), and they are also available in the National Guideline Clearinghouse (http://www.guideline.gov/). Copyright © 2012 European Association of Urology. Published by Elsevier B.V. All rights reserved.

Klinefelter's syndrome is the most common genetic cause of human male infertility, but many cases remain undiagnosed because of substantial variation in clinical presentation and insufficient professional awareness of the syndrome itself. Early recognition and hormonal treatment of the disorder can substantially improve quality of life and prevent serious consequences. Testosterone replacement corrects symptoms of androgen deficiency but has no positive effect on infertility. However, nowadays patients with Klinefelter's syndrome, including the non-mosaic type, need no longer be considered irrevocably infertile, because intracytoplasmic sperm injection offers an opportunity for procreation even when there are no spermatozoa in the ejaculate. In a substantial number of azoospermic patients, spermatozoa can be extracted from testicular biopsy samples, and pregnancies and livebirths have been achieved. The frequency of sex chromosomal hyperploidy and autosomal aneuploidies is higher in spermatozoa from patients with Klinefelter's syndrome than in those from normal men. Thus, chromosomal errors might in some cases be transmitted to the offspring of men with this syndrome. The genetic implications of the fertilisation procedures, including pretransfer or prenatal genetic assessment, must be explained to patients and their partners.