Human dicentric Y chromosomes. Case report and review of the literature.

A phenotypic female with histological evidence of mixed gonadal dysgenesis, and 45,X/46,X,dic(Yq) mosaicism is described. A review of the literature yielded 15 additional cases of dicentric Y chromosomes. Among the cases, a wide range of variation in phenotype, external genitalia, histology, and chromosomal findings was observed. Factors possibly contributing to such variability are discussed and include: the exact site of breakage and exchange in the Y chromosome; the timing of dicentric formation (meiotic vs mitotic); the occurrence of non-disjunction; and the presence or absence of a Y chromosome in cells of the gonadal anlage during a critical ontogenic period.