Prenatal diagnosis, sonographic findings and molecular genetic analysis of a 46,XX/46,XY true hermaphrodite chimera.

OBJECTIVES: To present the prenatal diagnosis, sonographic findings and, molecular genetic analysis of a 46,XX/46,XY true hermaphrodite chimera and to review the literature.

CLINICAL SUBJECT AND METHODS: Amniocentesis was performed at 22 weeks' gestation because of sonographic diagnosis of ambiguous genitalia. Initial amniocentesis, repeat amniocentesis, and cordocentesis revealed a mixture of 46,XX cells and 46,XY cells. Polymorphic DNA marker analysis using the fetal and parental blood was applied to investigate the genetic origin of the chimera. A 3,625-g baby was delivered at 37 weeks' gestation with clitoromegaly, prominent labia majora, fusion of the labia, and an orifice of the urogenital sinus. A lymphangioma was noted over the right arm and was excised at age 3 days. Extraembryonic tissues and the infant's skin were cytogenetically and molecularly studied.

RESULTS: Initial amniocentesis, repeat amniocentesis, and cordocentesis revealed the karyotype of 46,XX[12]/46,XY[9], 46,XX[15]/46,XY[12], and 46,XX[27]/46,XY[15], respectively. The cytogenetic results of the extraembryonic tissues and skin were consistent with prenatal diagnosis. Informative sex chromosome and pericentromeric autosome markers demonstrated double paternal and single maternal genetic contributions.

CONCLUSIONS: Prenatal sonographic diagnosis of ambiguous genitalia should alert true hermaphroditism and prompt thorough genetic investigations. DNA marker analysis is helpful in delineation of true fetal chimerism as well as determination of its genetic origin in prenatally detected 46,XX/46,XY chromosome complement.