Meiotic segregation in spermatozoa of a 46,X,t(Y;10)(q11.2;p15.2) fertile translocation carrier

Translocations involving gonosomes are frequent in azoospermic patients and sometimes in oligozoospermic ones, conditions that lead to request for assisted reproduction treatment. This study reports an unexpectedly fertile 49-year-old man bearing a de-novo translocation 46,X,t(Y;10)(q11.2;q15.2) associated with a high chromosomal risk for offspring, and referred for familial investigations after the diagnosis of an unbalanced translocation 46,XX,der(10)t(Y;10)(q11.2;p15.2) in his naturally conceived and mentally retarded daughter. Chromosome molecular investigation confirmed Y long-arm inheritance in the daughter and absence of the Yq deletion in the father. Semen analysis showed a normal sperm count associated with moderate asthenospermia and severe teratospermia. A total of 984 spermatozoa were analysed using fluorescence in-situ hybridization (FISH). Alternate segregation pattern was found in 50.31% of the spermatozoa studied. The frequencies of adjacent I, adjacent II, 3:1 segregation, and diploidy (or 4:0 segregation) were respectively 39.62, 1.63, 7.83, and 0.61%. No interchromosomal effect was observed. This patient is the first fertile man in whom the meiotic segregation pattern of a Y-autosome translocation has been analysed. The imbalance risk was close to those observed for reciprocal translocations, and emphasizes the value of FISH studies in males with a chromosomal translocation in order to provide them a personalized risk evaluation.