The Value of Molecular Analysis Using SRY and Amelogenin Genes in Sex Determination among Patients with Sex Differentiation Disorders

Abstract

Fifteen patients were referred with provisional diagnosis of intersex from hospitals or private clinics of different geographical regions in Sudan to the Department of Clinical Genetics at the Radiation and Isotopes Center, Al Neelain Medical Research Center, and Elite Clinic for cytogenetic and/or molecular diagnosis. Of the 15 patients, 11 of them (73.3%) were raised as females, while 4 of them (26.7%) were raised as males; those patients were diagnosed by The Sudanese Intersex Working Group according to the medical history, physical examination, ultrasound, hormonal analysis, cytogenetic, and molecular studies. The aim of this study was to determine the value of molecular analysis using SRY and Amelogenin genes in sex determination among patients with sex differentiation disorders by detection of presence or absence of SRY gene (sex determining region on Y chromosome) and findings of amelogenin gene (amelogenin gene found in both X and Y chromosomes with different molecular weights) in association with karyotyping. Venous blood samples were taken from every patient to detect the presence or absence of SRY gene and the amelogenin gene findings compared with the karyotyping of all patients. . DNA extraction was done and then PCR (polymerase chain reaction) was held to detect the presence or absence of SRY gene and amelogenin gene findings (either indicate XX or XY chromosomes). The results of this study showed that 12 patients (80%) found to have XY karyotype, SRY positive and amelogenin findings showing XY pattern. One patient (6.7%) had XY chromosomes, SRY present, and amelogenin findings showing XX. Another patient (6.7%) resulted in XX chromosomes, SRY present, and amelogenin findings indicated presence of XY chromosomes. The last patient (6.7%) had a mosaic karyotype (XX/XY), SRY positive and the amelogenin findings showed XY pattern. These results indicated that the sex determination can never be based on the detection of amelogenin gene alone, but rather on the karyotyping and SRY gene, because the amelogenin gene never tells about mosaic conditions and SRY gene translocation, while karyotyping and SRY gene do.