POLYMORPHIC DETECTION OF A PARTHENOGENETIC MATERNAL AND DOUBLE PATERNAL CONTRIBUTION TO A 46,XX 46,XY HERMAPHRODITE/

True hermaphroditism in humans usually is associated with a 46,XX kary otype or with mosaicism in which admixtures of cells with an XX and an XY karyotype are seen. However, the mechanisms that cause such mosaic isms are poorly understood. To date, with rare exceptions, analyses of hermaphrodites have been limited mostly to cytogenetic investigations . In this report, we describe a 5-year-old patient with true hermaphro ditism and a 46,XX/46,XY karyotype (ratio 38:12) in lymphocytes, sugge sting involvement of two fertilization events. Microsatellite DNA poly morphisms distributed throughout the genome were analyzed, to investig ate the origin of the cell lines concerned. The results are consistent with double paternal and single maternal genetic contributions. Possi ble mechanisms that would explain these findings are discussed. The mo st likely mechanism involves a single haploid ovum dividing parthenoge netically into two haploid ova, followed by double fertilization and f usion of the two zygotes into a single individual, at the early embryo nic stage.