DETECTION OF SRY IN 45,X 47,XYY MOSAICISM LEADING TO PHENOTYPIC FEMALE/

SRY on the Y chromosome initiates male sex determination. We tested a phenotypic female with sex chromosome mosaicism, X/XYY, for SRY expres sion. SRY was determined by polymerase chain reaction (PCR) amplificat ion in genomic DNA from a female patient with a sex chromosome mosaic complement, 45,X/47,XYY, followed by sequencing analyses. The patient yielded the PCR product with predicted size and homology to the consen sus sequence of SRY. The demonstration of SRY provides evidence that t he female phenotype in the presence of sex chromosome mosaicism, X/XYY , may result from alterations in another part of the sex-determining p athway or downstream from SRY.