A girl with family history of a disorder of sex development (DSD) was referred for biochemical investigations and genetic analysis. Parents were consanguineous and a sibling was thought to have partial androgen insensitivity although androgen receptor gene analysis does not fully explain the phenotype. A maternal uncle with perineal hypospadias and a maternal aunt also had the mutation. One sister was normal, one brother had dextrocardia and another brother had mental retardation. Antenatal diagnosis was 46XY with transmission of the defective androgen receptor gene. There were no perinatal complications. The external genitalia were female, labia folds were not fused, gonads were palpable, there was a normal clitoris with vaginal opening. On day 4 the plasma DHAS was 1.68 nmol/l, androstenedione was 19.5 nmol/l, testosterone was 4.3 nmol/l suggesting a defect of 17-ketosteroid reductase. Further androstenedione:testosterone ratios were normal. No uterine tissues were seen on ultrasound, kidneys were normal. On review it was concluded that the androstenedione assay was erroneous due to interference from fetal adrenal steroids as experienced with assays for testosterone and 17-hydroxyprogesterone in newborns. Biochemical tests for DSD are fraught with problems of reference ranges and assay specificity. A recent consensus on DSD diagnosis (Arch Dis Child 2006; 91:554563) made limited recommendations for laboratory investigations although such investigations are crucial to making a diagnosis. Results for steroids in many current assays without solvent extraction can be misleading and steroid concentrations in newborns should be determined with high specificity assays.
06 - 07 Nov 2006
Society for Endocrinology