Abnormal synaptonemal complex in an oligochiasmatic man with spermatogenic arrest

A 46, XY azoospermic patient with a very low chiasma frequency at diakinesis-first metaphase was found to have an abnormally high ratio between the number of cells at late leptotene-early zygotene and at pachytene, as well as unpaired chromosome regions and absence of an XY body at pachytene, and a defective formation of the synaptonemal complex. The abnormalities observed at first meiotic prophase indicate that the reduced chiasma frequency was secondary to a primary defect in chromosome pairing. The high proportion of parental consanguinity and of presumably affected sibs in the families of the few oligochiasmatic patients reported earlier suggests a recessive meiotic mutation.