Unique case of deletion and duplication in the long arm of the Y chromosome in an individual with ambiguous genitalia

Human Y chromosome is made up of almost an equal amount of euchromatin and heterochromatin. The heterochromatic region is interspersed in the distal region of the long arm of the Y chromosome (Yq), which consists of two classes of repetitive sequences, namely, DYZ1 [Nakahori et al., 1986] and DYZ2, containing 4,000 and 2,000 copies, respectively [Manz et al., 1992]. Although the exact function of the heterochromatin is not yet properly understood, it is believed that quantitative variation in the heterochromatin is an evolutionary phenomenon, having no phenotypic effect [Nazarenko et al., 1987]. Paracentric inversion in Yq was reported earlier in an individual with ambiguous genitalia [Liou et al., 1997]. Here we report a case with ambiguous genitalia and undescended testis having an apparently normal 46,XY karyotype. Molecular analysis revealed a deletion of the entire heterochromatic region (Yq12) and a duplication of the euchromatic region (Yq11). The proband was a 5-year-old child having ambiguous genitalia and undescended testis. The child was born to a nonconsanguineous parents. The mother was 29 years old and the father was 32 years old at the time of the proband’s birth. Delivery was full term and normal. Besides the above phenotypic abnormality, the proband did not have any other obvious abnormality. The 3-yearold younger sister of the proband was normal. Gonadal

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