Rare rearrangements: a "jumping satellite" in one family and autosomal location of the SRY gene in an XX male

Abstract

A satellited short arm of the Y chromosome (Yps) is rare. Only one de novo case of Yps has been documented. Here we report the prenatal diagnosis of Yps in a male fetus with a karyotype, 46,XYps. Family chromosome study showed that the father and a sister had a satellited short arm of the X chromosome (Xps). A phenotypically normal male child with the Yps was delivered. This is the first familial case showing a satellite "jumping" from Xp to Yp. We propose that it resulted from a crossover within the pseudoautosomal region 1 (PAR1) on the distal Xp and Yp during paternal meiosis. In addition to the rare translocation mentioned above, relocation of the SRY gene onto an autosome in XX males is also a rare event. Herein we report a phenotypically normal male fetus with a 46,XX karyotype. Fluorescence in situ hybridization (FISH) study showed that the SRY locus had been transferred to the terminal short arm of a chromosome 3. The terminal short arm deletion of this chromosome 3 was also confirmed by FISH study with a subtelomeric probe and the breakpoint of the terminal deletion was estimated between 446 and 664 kb from the 3p telomere by real-time qPCR study with a gene sequence and STS markers in this region. A healthy boy was delivered at 37 weeks of gestation. At 1-year follow-up, the child's growth pattern and development were appropriate for age.