Molecular diagnosis of 5α-reductase-2 gene mutation in two Indian families with male pseudohermaphroditism

Aim： To identify the genotype of two Indians with male pseudohermaphroditism. Methods： Standard radioimmunoassay procedure was used for estimating hormonal levels. Conventional cytogenetic analysis was carded out for diagnosing the genetic sex in these subjects with genital ambiguity. Molecular analysis was carried out by standard polymerase chain reaction procedure using different sets of primers and reaction conditions specific for the 5α- reductase type 2 gene （SRDSA2） gene. Direct sequencing was carried out using the ABI Prism dye terminator sequencing kit and the ABI 310 sequencing apparatus. Results： We found an SRDSA2 gene mutation in exon 5, where arginine is substituted with glutamine （R246Q）, in two males with pseudohermaphroditism and ambiguous genitalia from unrelated families. This is the first time this mutation has been reported in individuals from India. Conclusion： Identification of the R246Q mutation of the SRDSA2 gene from two unrelated Indian families possibly extends the founder gene effect.

Isolated micropenis reveals partial androgen insensitivity syndrome confirmed by molecular analysis

Partial androgen insensitivity syndrome （PAIS） is the milder variant of androgen receptor （AR） defects. The subtle effects of AR mutations present in a patient with micropenis, peno-scrotal hypospadias, infertility, clitoromegaly and posterior labial fusion. We studied the association of isolated micropenis with the genetic defects resulting in androgen resistance, that is, AR gene defects and 5-α reductase type 2 （SRD5A2） deficiency. We describe two cases of isolated micropenis： one in a 14-year-old boy and the other in a 3-year-old boy who was followed until he was 10 years old. There were no findings of hypospadias, cryptorchidism or gynecomastia in either of these patients. Serum gonadotrophin and androgen levels were obtained and karyotyping was done. Human chorionic gonadotropin （hCG） stimulation testing assessed the functional capacity of the testes. DNA was extracted from peripheral leukocytes, and all exons of the SRD5A2 and AR genes were amplified by polymerase chain reaction and sequenced. In both patients, baseline testosterone （T） level was low and the values were elevated after hCG testing. The sequence of the SRD5A2 gene was normal in patient 1, and a heterozygous polymorphism, V89L, was found in patient 2. Two known mutations, P390S and A870V, were identified in patients 1 and 2, respectively. Mutations in the AR gene can be associated with isolated micropenis without other features of PAIS, such as hypospadias or gynecomastia. This underlines the importance of including AR gene analysis in the evaluation of isolated micropenis with normal plasma T to ensure proper management of the patient and appropriate genetic counseling for the family.

A novel E153X point mutation in the androgen receptor gene in a patient with complete androgen insensitivity syndrome

Aim:To study a 46,XY newborn patient with a phenotype suggestive of an androgen insensitivity syndrome toconfirn an anomaly in the AR gene.Methods:Genomic DNA from leukocytes was isolated in order to analyze SRYgene by PCR and sequencing of the eight exons of AR gene.Isolation of human Leydig cell mesenchymal precursorsfrom the testis was performed in order to study testosterone production and response to hCG stimulation in culture.Results:Surgical exploration disclosed two testes,no Wolffian structures and important Mullerian derivatives.TheSRY gene was present in peripheral blood leukocytes.Sequencing of the AR gene evidenced a previously unreported Gto T transversion in exon 1 that changed the normal glutamine 153 codon to a stop codon.Interstitial cell culturesproduced sizable amounts of testosterone and were responsive to hCG stimulation.Conclusion:This E153X nonsensepoint mutation has not been described previously in cases of AIS,and could lead to the synthesis of a short truncated(153 vs 919 residues)non functional AR probably responsible for the phenotype of complete androgen insensitivitysyndrome(CAIS).