Y chromosome microdeletions and germinal mosaicism in infertile males

Molecular deletions of the Y chromosome long arm are a frequent cause of ma le infertility. Because these deletions are thought to be inherited from fa thers without Y chromosome deletions, the question arises as to whether the ir relatively high incidence in the male population could be due to the exi stence of a mosaicism in somatic and/or germinal paternal cells. This study included a total of 181 infertile men, among whom 18 were found to have an abnormal karyotype. In the other 163, polymerase chain reaction (PCR) anal ysis detected nine (5.5%) Y chromosome microdeletions. Blood, spermatozoa o r testicular cells from 47 men (27 oligozoospermia, 20 azoospermia), includ ing six Y-deleted patients, were screened for mosaicism using double target fluorescence in-situ hybridization (FISH) with Y centromeric and deleted i n azoospermia (DAZ) gene-specific probes. Results indicated that: (i) perce ntages of double (intact Y chromosome) or single (deleted Y chromosome) flu orescent signals by FISH were in agreement with PCR data, thus demonstratin g the reliability of the method; and (ii) a weak germ cell mosaicism was fo und in only two oligozoospermic patients, carrying 1.97 and 4.13% respectiv ely of spermatozoa with a deleted Y chromosome. Further studies on larger p opulations are needed to evaluate precisely the incidence of Y deletion mos aicisms in infertile men.