Molecular investigation of two male subjects with short stature and a 45,X/46,X,ring(Y) karyotype.

We studied 2 subjects with a 45,X/46,X,ring(Y) karyotype. Both of them were evaluated because of short stature and a subnormal rate of linear growth. One patient had additional features of the Ullrich-Turner syndrome. Both subjects had normal male external genitalia. Two copies of the pseudoautosomal gene, MIC2, were present in DNA of each individual. All sequences examined on the Y-specific portion of the short arm, including those for the sex-determining region Y (SRY) gene, were present. By contrast, portions of the long arm of the Y chromosome were missing from DNA of both subjects. In subject 1, deletion intervals 6 and 7 were missing. In subject 2, deletion interval 5, distal to 5B, was missing in addition to intervals 6 and 7. The most likely explanation for the ring formation in these subjects is a chromosomal break in the long arm and in the pseudoautosomal region of the short arm distal to MIC2 with subsequent ligation of the remaining sequences on the long arm and short arm. However, a complex rearrangement cannot be excluded.