Hydrocephaly, penoscrotal transposition, and digital anomalies associated with de novo pseudodicentric rearranged chromosome 13 characterized by classical cytogenetic methods and mBAND analysis.

We report on a patient with hydrocephaly, penoscrotal transposition, oligodactyly, and minor anomalies. Comprehensive cytogenetic studies involving both classical cytogenetic methods and mBAND analysis were used to show a stable dicentric rearranged chromosome 13 that result in a 46,XY,psu dic(13;13)(13pter --> 13q32::13q11 --> 13pter) de novo karyotype. This aberration probably arose as a consequence of unequal sister chromatid breakage repair events. This report is the first to describe all of the most severe features associated with partial monosomy in one patient. Moreover, the delineation of monosomy 13q32 --> qter in this patient facilitates identification of the developmental genes responsible for the clinical features within this region of chromosome 13.