Absence of correlation between Sry polymorphisms and XY sex reversal caused by the M. m. domesticus Y chromosome.

Mus musculus domesticus Y chromosomes (YDOM Chrs) vary in their ability to induce testes in the strain C57BL/6J. In severe cases, XY females develop (XYDOM sex reversal). To identify the molecular basis for the sex reversal, a 2.7-kb region of Sry, the testis-determining gene, was sequenced from YDOM Chrs linked to normal testis determination, transient sex reversal, and severe sex reversal. Four mutations were identified. However, no correlation exists between these mutations and severity of XYDOM sex reversal. RT-PCR identified Sry transcripts in XYDOM sex-reversed fetal gonads at 11 d.p.c., the age when Sry is hypothesized to function. In addition, no correlation exists between XYDOM sex reversal and copy numbers of pSx1, a Y-repetitive sequence whose deletion is linked to XY sex reversal. We conclude that SRY protein variants, blockade of Sry transcription, and deletion of pSx1 sequences are not the underlying causes of XYDOM sex reversal.