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Journal of Applied Genetics 46(4), 2005, pp. 415-418

Ambiguous genitalia by 9p deletion inherent to a dic(Y;9)(q12;p24)

Ana I. Vasquez-Velasquez, Lisette Arnaud-Lopez, Luis E. Figuera, Jorge R. Padilla-Gutierrez, Fernando Rivas, Horacio Rivera

Abstract: We describe here a 3-month-old male infant with brachy-plagyocephaly, short neck, widely spaced nipples, mild hypertonia, and ambiguous external genitalia but with both testes in the scrotum and no Müllerian derivates. His karyotype was 45,X,der(Y;9)(q12;p24).ish der(Y;9)(DYZ3+,SRY+,9ptel-) de novo. This patient's impaired sex differentiation is consistent with gonadal dysgenesis and compares with the male-to-female sex reversal secondary to a partial 9p deletion in spite of an intact Yp or SRY locus documented in 24 patients including a sex-reversed girl with a (Y;9) dicentric derivative. As for the cytogenetic findings, this case represents the second instance of a de novo pseudodicentric (Y;9) chromosome with loss of both distal 9p and Yq12 regions, apparent intactness of SRY, and consistent or preferential inactivation of the Y centromere. In addition, the possible 9p23p-p22 duplication observed in this case evokes the concomitant 9p22-p21 duplication documented in the previous girl with a (Y;9) derivative. Hence, these striking similarities point to a nonrandom Y;9 rearrangement in patients with either sex reversal or gonadal dysgenesis. Even if the present pseudodicentric derivative had inactivated the Y centromere, the existence of some variant cells points to functional dicentricity as it has been documented in other Y;autosome dicentric derivatives.

Key words: 9p chromosome, deletion, sex reversal.

Correspondence: H. Rivera, Centro de Investigacion Biomedica de Occidente, Instituto Mexicano del Seguro Social, Ap. Postal 1-3838, Guadalajara, Jal., Mexico, e-mail:

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