Unconjugated estriol as an indication for prenatal diagnosis of steroid sulfatase deficiency by in situ hybridization

Background: Undetectable or very low unconjugated estriol (E3) levels in routine maternal serum screening are associated with steroid sulfatase deficiency, miscarriages, and anencephaly. Cases: Fluorescence in situ hybridization techniques were used in the diagnosis of steroid sulfatase deficiency prenatally in three cases with low or undetectable unconjugated E3 levels. Results showed a male fetus with a deleted steroid sulfatase region, but intact Kallmann syndrome region in all three cases. One mother was studied by fluorescence in situ hybridization and showed a similar deletion for steroid sulfatase gene in one copy of X chromosome (carrier). Conclusion: Women with undetectable or very low levels of estriol on serum screening should be counseled regarding steroid sulfatase deficiency with evaluation by fluorescence in situ hybridization.