Prevalence of chromosomal abnormalities in phenotypically normal and fertile adult males: large-scale survey of over 10,000 sperm donor karyotypes

BACKGROUND: Sperm donors represent an appropriate population for evaluating the frequency of chromosomal abnormalities in phenotypically normal and fertile adult males. METHODS: A large multicentric retrospective study was made within the French CECOS (Centre d'Etude et de Conservation des ufs et du Sperme) for collecting cytogenetic, biological and familial data in sperm donors over a 25-year period. RESULTS: As a whole, 10,202 karyotypes have been recorded. Thirty-eight karyotype aberrations (0.37%) have been diagnosed including 21 balanced chromosomal rearrangements (0.2%). These results are in agreement with those obtained in most large-scale studies performed in unselected newborns. Semen parameters were known for all men carrying an abnormal karyotype and showed normal sperm counts, suggesting that these types of chromosomal aberrations have no or poor consequences on spermatogenesis. Available familial data did not reveal any particular history of malformations, mental retardation or fetal losses. CONCLUSION: This study is the first large-scale cytogenetic study made in normal and fertile males and shows that the frequency of chromosomal aberrations is not influenced by a previous normal fertility or by an uneventful familial history when compared to that found at birth.