Linear increase of diploidy in human sperm with age: A four-colour FISH study

The aim of this study was to determine if donor age is associated with an i ncreased incidence of diploidy and of disomy for the sex chromosomes and fo r chromosomes 6 and 21. We used simultaneous fluorescence in situ hybridisa tion (FISH) for chromosomes 6, 21, X and Y in sperm from 18 healthy donors, aged 24-74 years (mean 48.8 years). A total of 194 024 sperm were analysed , with a minimum of 10 000 sperm scored for each donor. Our results indicat e a significant increase of the level of diploidy (P = 0.002), and a margin al significance of total sex chromosome disomy (P = 0.055) with age. No inc rease was observed for disomies XX, YY, XY, 21 or 6. The percentages of inc rease for disomy and for diploidy ranged from 0.3 to 17% for each 10-year p eriod. Chromosomes 6 and 21 did not segregate preferentially with the X or Y chromosomes. Our findings show a linear trend association between age and diploidy inhuman males.