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Analysis of the testis-determining gene SRY in patients with XY gonadal dysgenesis
O Tsutsumi1, T Iida, Y Nakahori
1Department of Obstetrics and Gynecology, Faculty of Medicine, University of Tokyo, Japan.
Abstract:
The sex-determining region of the Y chromosome (SRY) encodes a gene that has many of the properties expected to the testis-determining factor. XY gonadal dysgenesis is characterized by streak gonads in phenotypic females who lack the somatic abnormalities and short stature associated with Turner's syndrome. We have examined four patients with XY gonadal dysgenesis for the presence and absence of SRY and the DNA sequence of the gene. The results showing that one was negative for SRY and another had a mutation within the gene have confirmed the etiological role of SRY in XY gonadal dysgenesis. However, the other two patients with short stature had apparently normal SRY. DNA sequencing of the SRY gene showed 100% nucleotide sequence identity with the reported cloned sequence. Sex reversal in two of the present cases may be due to mutation at a locus other than SRY in the sex-determining pathway, a gene potentially involved in the determination of human sexual constitution.
Insights
Mutations in the sex-determining region of the Y chromosome (SRY) gene cause XY gonadal dysgenesis. However, normal SRY genes in some patients suggest other genetic factors influence sex determination.
Area of Science:
- Genetics
- Developmental Biology
- Human Genetics
Background:
- The sex-determining region of the Y chromosome (SRY) gene is crucial for male sex determination.
- XY gonadal dysgenesis presents as streak gonads in individuals with a male karyotype, lacking Turner syndrome features.
- Understanding SRY's role is key to diagnosing and understanding disorders of sex development.
Observation:
- Four patients with XY gonadal dysgenesis were analyzed for SRY gene presence and sequence.
- One patient lacked the SRY gene entirely.
- Another patient exhibited a mutation within the SRY gene sequence.
Findings:
- The absence or mutation of SRY confirmed its etiological role in XY gonadal dysgenesis for two patients.
- Two patients with short stature presented with apparently normal SRY genes, showing 100% nucleotide sequence identity to controls.
- These findings indicate that SRY is not the sole determinant in all cases of XY gonadal dysgenesis.
Implications:
- The study implicates SRY mutations in a subset of XY gonadal dysgenesis cases.
- Normal SRY in some patients suggests alternative genetic pathways or loci involved in human sex determination.
- Further research into other genes within the sex-determining pathway is warranted to explain sex reversal in these cases.