Analysis of the SRY gene in two sex-reversed XY sisters identifies two new novel point mutations in the high mobility group box domain

Objective: To determine mutations in the SRY gene in two sisters with 46, XY karyotype. Design: Case report. Setting: Jamia Millia Islamia, New Delhi, and CSIRO Human Nutrition, Adelaide, Australia. Patient(s): Two sisters aged 23 and 27 years old with primary amenorrhea. Intervention(s): Endocrine, mutations in the SRY gene, and DNA binding ability. Main Outcome Measure(s): LH, FSH, and testosterone levels, DNA sequence findings. Result(s): We found a new point mutation in the SRY gene in patient 1 at position +275 (A>T), which results in amino acid change (K92M). In patient 2, we found a double mutation in the SRY gene at two different loci. The first mutation is a substitution of C at +352, resulting in a change of amino acid (A118P), and second is deletion of T, resulting in a frame shift within a highly conserved DNA-binding motif-high mobility group box at +379 (T127IfsX179). Electrophoretic mobility shift assay showed that mutant K92M and A118P show reduced and greatly reduced binding ability, respectively. These mutations have the potential to interfere with protein-DNA binding activity and nuclear localization necessary for interactions of these proteins with DNA. Conclusion(s): Our results suggest involvement of the SRY gene in sex reversal, which supports the relationship between SRY alterations, gonadal dysgenesis, and/or primary infertility, and provides further evidence of a high-mobility group box significance in DNA-binding/-bending properties.