Use of Y chromosome specific probes to detect low level sex chromosome mosaicism.

An individual found to be a true hermaphrodite at laparotomy, is presented. Cytogenetic studies which initially disclosed a 46,XX karyotype, conflicted with the anatomic presence of a testis. More extensive analysis of peripheral lymphocytes and skin fibroblasts revealed low level 46,XX/69,XXY mosaicism. DNA hybridization studies, using highly repeated Y chromosome specific probes, confirmed the rare presence of Y chromosome bearing cells. Such combined clinical and molecular studies can have an important impact on diagnosis and management of cases in which sex chromosome mosaicism is suspected.