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Objective: Analysis of the 5alpha-reductase type 2 (SRD5A2) gene in Egyptian patients with suspected 5alpha-reductase (5alphaR) deficiency., Patients and Methods: Eight unrelated patients, originating from different geographical areas of Egypt, were referred to the Department of Pediatrics. Six prepubertal and two postpubertal patients presented with ambiguous genitalia. Four were being reared as females while the others were being reared as males. Six patients were products of consanguineous marriages. All patients had 46,XY karyotype. Basal and post-human chorionic gonadotrophin (hCG) stimulation plasma levels of testosterone and dihydrotestosterone were determined. Sequencing of five exons of the SRD5A2 gene was carried out., Results: All patients had normal male testosterone levels, both basal and post-hCG stimulation. The T/DHT ratio was available for six patients and showed values that ranged from normal to high. Three different homozygous mutations were identified. One patient carried a Y235F substitution and two had a N160D substitution. Interestingly, all five of the other patients had the G34R mutation. The parents were heterozygous for the mutations, although the mother of one patient was homozygous for the G34R mutation., Conclusion: Among eight unrelated Egyptian children with 5alpha-reductase deficiency, the G34R mutation was identified in five patients. The high consanguinity rate in Egypt suggests a common ancestor with a founder gene effect in cases of G34R mutation.

Unlabelled: The molecular basis for male pseudohermaphroditism produced by the 5 alpha-reductase deficiency is becoming increasingly understood., Objective: We have performed biochemical and molecular analyses of the 5 alpha-reductase type 2 gene in a Turkish family with a 5 alpha-reductase deficiency., Patient: A 46,XY prepubertal Turkish patient with female phenotype showing clitoral hypertrophy, high plasma testosterone and dihydrotestosterone, and normally differentiated and developed testosterone-dependent internal genitalia., Measurements: 5 alpha-Reductase activity, measured by the conversion of 3H-T into 5 alpha-reduced compounds, was determined from cultured genital skin fibroblasts by both intact monolayer assay and cell-free extracts at various pH values. The five exons of the 5 alpha-reductase type 2 gene were sequenced after enzymatic amplification (PCR) of the patient's genomic DNA. Labelled PCR of the consanguineous parents' DNA was submitted to electrophoresis on a sequencing gel., Results: A marked decrease in the transformation of T into 5 alpha-reduced compounds by intact cells and a diminished 5 alpha-reductase activity at acidic pH by sonicated cell extracts strongly suggested a 5 alpha-reductase type 2 deficiency. Molecular analysis of the 5 alpha-reductase type-2 gene showed a trinucleotide deletion straddling codons 156 and 157, responsible for a methionine residue deletion at position 157 of the protein. The parents' DNA contained both normal and deleted alleles., Conclusions: This is the third deletion described in the 5 alpha-reductase type 2 gene. The deleted methionine 157 is conserved in both types 1 and 2 of human and rat 5 alpha-reductase, which suggests its crucial role in the functioning of the enzyme. This gene rearrangement was thus clearly responsible for the reduced 5 alpha-reductase activity and abnormal genital development in this patient.

Objective: Partial androgen insensitivity syndromes are the cause of genital ambiguity that is at times quite severe; there is, therefore, a high demand for prenatal diagnosis in families already afflicted with this syndrome. When the mutation has not been identified, the diagnosis can be made by the study of the polymorphisms of the androgen receptor gene. To perform molecular prenatal diagnosis in a family with partial androgen insensitivity syndrome, we studied the Hind III polymorphism of the androgen receptor gene on the trophoblastic DNA. The use of this restriction fragment length polymorphism tracked maternal X chromosome segregation and established prenatal diagnosis although the mutation had not yet been identified in this family. FAMILY: The mother had been previously described as heterozygous for the Hind III polymorphism and chromosomal segregation analysis showed that the affected allele was associated with the 6.7-kb Hind III fragment., Measurements: Hind III RFLP with an androgen receptor gene cDNA probe was realized on the trophoblastic DNA, along with measurement of androgen binding activity on the trophoblastic cells., Results: We detected the presence of the 6.7-kb fragment in the DNA of the trophoblastic cells suggesting the fetus was affected. Partial androgen insensitivity syndrome was confirmed by a considerable decrease in androgen binding activity on the trophoblastic cells and by sonography of the fetus. After a therapeutic abortion requested by the parents, the diagnosis was confirmed by clinical examination of the fetus, biochemical analyses of the fetal androgen receptor, and molecular studies of the fetal DNA., Conclusions: When the mutation of the androgen receptor gene has not been identified, Hind III polymorphism of the trophoblastic DNA is useful in the prenatal diagnosis of androgen insensitivity syndrome in high-risk families.