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Xp-duplications with and without sex reversal
A Baumstark1, G Barbi, M Djalali
1Abteilung Medizinische Genetik, Universität Ulm, Germany.
Human Genetics
|January 1, 1996
Summary
Xp duplications including the dosage sensitive sex reversal (DSS) region can cause male to female sex reversal. The degree of genitalia development depends on gene-driven degeneration within the DSS region.
Area of Science:
- Genetics
- Developmental Biology
- Endocrinology
Background:
- Duplications in the short arm of the X chromosome (Xp), particularly involving the dosage sensitive sex reversal (DSS) region, are known to cause male-to-female sex reversal.
- Understanding the precise genetic mechanisms and phenotypic outcomes of Xp duplications is crucial for diagnosing and managing related congenital conditions.
Purpose of the Study:
- To investigate the clinical, cytogenetic, and molecular characteristics of two patients with Xp duplications.
- To correlate the extent of Xp duplication, especially within the DSS region, with the resulting sex reversal and associated phenotypes.
- To compare findings with previously reported cases to elucidate genotype-phenotype relationships.
Main Methods:
- Case study of two patients with Xp duplications and sex reversal.
- Karyotyping and cytogenetic analysis.
- Quantitative Southern blot analysis to define the duplicated region on Xp (Xp22.13 to p21.2).
- Clinical assessment and comparison with existing literature.
Main Results:
- Two patients with Xp duplications were analyzed: one 46,XY individual with female genitalia and another with male genitalia but abnormalities.
- Quantitative Southern blot confirmed duplications in the Xp21.3-pter region, with breakpoints near the DSS locus in one case.
- Comparison with 22 previously reported Xp duplication cases revealed that 9 had female genitalia with DSS duplication, and 2 had ambiguous genitalia.
- Extragenital symptoms were non-specific and showed no significant difference between patients with or without sex reversal.
Conclusions:
- Xp duplications, including the DSS region, can lead to male-to-female sex reversal.
- While testicular tissue induction may initiate, the final genitalia phenotype appears dependent on the degree of degeneration influenced by genes within the DSS region.
- Phenotypic variability exists, with extragenital features being generally non-specific across affected individuals.