抄録
Mutations in the sex-determining gene SRY previously identified occur in the 46, XY females. In this study, we investigated whether the SRY mutation participates in the onset of XY sex reversal. Genomic deoxyribonucleic acids (DNA) from five XY sex-reversed females were analyzed for mutations in SRY using polymerase-chain reaction (PCR) amplification and subsequent DNA sequencing. One of the 46, XY females suffered a novel missense mutation at position 306 of SRY gene, wherein cytosine was replaced by adenine (CGC→AGC), resulting in a substitution of serine for arginine at amino acid position 76 of SRY protein. This mutation was located in Helix I of the high-mobility-group (HMG) domain. No other mutations were found in the remaining regions of the gene. Analysis of the SRY gene in her father revealed that he carried the identical mutation version. This substitution introduces a large basic for a small polar uncharged amino acid residue in the HMG box. The fact that the father transmits the mutant SRY copy to his offspring implies that SRY mutations do not always occur in association with sex reversal, even when the ionic environment is altered.
