Localization of the SRY Gene on Chromosome 3 in a Patient with Azoospermia and a Complex Karyotype 45,X/46,X,i(Y)(q10)/46,XX/ 47,XX,i(Y)(q10)

Abstract

This study aimed to identify the cause of azoospermia in a 38-year-old infertile man who was referred for genetic testing. Cytogenetic evaluation was performed by G-banding, C-banding, and FISH using centromeric probes for chromosomes X and Y and showed the presence of a monocentric isochromosome Y with a complex, mosaic karyotype 45,X/46,X,i(Y)(q10)/46,XX/47,XX,i(Y)(q10). Multiplex PCR for the commonly deleted genes in the AZFa, AZFb, and AZFc regions of the Y chromosome was performed and indicated the presence of all 3 regions. Further, PCR amplification followed by DNA sequencing of the SRY gene was done, which ruled out mutations in that gene. To identify the position of the SRY gene, FISH using a locus-specific probe was used and showed that the gene had been translocated to chromosome 3. Subtelomere FISH for 3q and Yp evidenced that the subtelomeric region of the Y chromosome was found on the terminal region of 3q. The clinical symptoms of the patient can be attributed to this abnormal genotype. The importance of genetic testing in infertile patients and the need for genetic counselling to prevent the transmission of the defect are emphasized.