Presumed Impairment of the X Inactivation During Meiotic Prophase: A Common Phenomenon Causing Spermatogenic Breakdown in Various Cytogenetic Conditions

Abstract

Balanced autosomal translocations aremore frequently observed in men attending an infertility clinics that in general population (1). The sterilizing effects of these autosomal translocations appear to disturb gamete production in male heterozygotes, meanwhile no effects have been reported in females carrying the same translocation (1). The mechanism of spermatogenic breakdown is unclear: some translocations are associated with severe oligospermia, azoospermia and subsequent sterility; others have no effect on gamete production. Moreover, both sterility and fertility were observed in translocation carriers from the same family (2). Various tentative explanations have been proposed in the past (3): the position effect of the genes or a mutation associated with one or both of the break points leading to pairing disturbance and a high frequency of univalents.