Abstract:OBJECTIVE: To investigate the value of direct sequencing of sex-determining region Y (SRY) gene, as well as peripheral blood karyotype analysis, in the diagnosis of disorders of sex development (DSD) among children and adolescents with ambiguous genitalia. METHODS: The karyotypes of 20 children and adolescents with ambiguous genitalia were determined by conventional G-banding analysis. PCR amplification was used to detect SRY gene in these patients, and direct sequencing was used to judge whether there was SRY gene mutation. RESULTS: Of the 20 cases, 17 were positive for SRY gene, and 3 were negative for SRY gene. Direct sequencing revealed no SRY gene mutation in the positive cases, however karyotype analysis found 4 special karyotypes in these patients: 46, XY, del(Y) (q12)/45, X; 46, XY, add(Y) (p11); 46, XY, r(9); 46, XY, 9qh+. CONCLUSIONS: SRY gene detection can help determine the type of DSD among children and has the advantage of quick detection. Used together with G-banding analysis, it is helpful for primary diagnosis of DSD among children.