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Fetal gender: antenatal discrepancy between phenotype and genotype
F Bretelle1, L Salomon, M-V Senat
1Department of Obstetrics and Gynecology, Paris-Ouest University, CHI Poissy-St-Germain, France.
Summary
Sexual discrepancy in fetal karyotypes (e.g., 46,XX males, 46,XY females) requires careful evaluation. Investigations should exclude sample errors and placental mosaicism, and consider genetic testing for Y chromosome genes.
Area of Science:
- Genetics
- Reproductive Biology
- Developmental Biology
Background:
- Sexual discrepancy, including 46,XX males and 46,XY females, is often diagnosed postpubertally.
- Sex reversal conditions present complex diagnostic challenges.
- Understanding the genetic and developmental basis of sex determination is crucial.
Observation:
- Three cases of sexual discrepancy were identified through prenatal diagnostic methods: genetic amniocentesis, chorionic villus sampling, and fetal blood sampling.
- Discrepancies were noted between fetal karyotype and ultrasonographic phenotype.
- These cases involved conditions such as 46,XX male, 45,X male, and 46,XY female.
Findings:
- Prenatal detection of sexual discrepancy necessitates excluding sample error and placental mosaicism.
- Detailed fetal ultrasound is vital for identifying syndromic presentations of gender discrepancy.
- The etiologies of various sex reversal conditions were reviewed.
Implications:
- Early identification of sexual discrepancy through prenatal testing allows for timely intervention and genetic counseling.
- Further investigation, including Y chromosome gene localization (e.g., SOX genes), is recommended when repeat karyotyping is indicated.
- This highlights the importance of integrating cytogenetic and phenotypic data in prenatal diagnosis.