Differential associative behaviour of mitotic and meiotic acrocentric chromosomes

XY-quadrivalent association and sterility in a man carrier of a reciprocal autosomal translocation involving the whole arm of an acrocentric chromosome t(2;15)(q21.3;cen)

Meiotic and synaptonemal complex studies using electron microscopy were carried out on an infertile man with a 46,XY t(2q;15p). Synaptonemal complex analysis showed terminal asynapsis in the totality of quadrivalents and a high and significant frequency of association with the XY vesicle (80%), possibly related to the high amount of satellite DNA of the acrocentric chromosome 15. In this translocation carrier, the XY quadrivalent association at pachytene stage is positively correlated with the degree of spermatogenic breakdown after pachytene stage. Whether association with the non-paired segment represents the causative factor or only a secondary effect has still to be clarified.