A novel insA2933 causes premature termination of translation and is accompanied by overexpression of truncated androgen receptor gene in a patient with complete androgen insensitivity syndrome

A patient with a female phenotype, 46,XY karyotype, and a diagnosis of complete androgen insensitivity syndrome (CAIS) was examined. Her mother and three 46,XX sisters were also included in the study. Sequence analysis of the androgen receptor gene (AR) revealed a novel A2933 insertion that alters the Tyr codon to a termination codon (Y857X), resulting in a truncated form of the receptor. Computer simulation revealed major conformational changes in the hydrophobic pocket that accommodates the hormone. An insA2933 results in a truncated receptor incapable of binding the ligand and is responsible for the clinical symptoms of CAIS in the patient. The levels of the AR transcript in peripheral blood leukocytes were higher in the patient than in her heterozygous mother and her heterozygous sister, as well as in the two healthy sisters. It is hypothesized that elevated levels of the AR transcript in the patient might be caused by the inability of the truncated receptor to react with IFI-16, which functions in complex with AR to inhibit the expression of the AR gene.

A correlation between the heterogeneity of hypervariable region 1 of E2 glycoprotein of Hepatitis C virus (HCV) and HCV antibody profile: a case study

A correlation between the heterogeneity of hypervariable region 1 (HVR1) of E2 glycoprotein (gp) and Hepatitis C virus (HCV) antibody profile was investigated. Of 6 patients studied two were in acute phase, two in chronic phase and two showed signs of long-time HCV infection, i.e. liver cirrhosis. All the patients exhibited a vigorous antibody response to viral proteins C, NS3, NS4 and NS5. An antibody response to HVR1 of E2 was found in one patient in acute phase and in one or two patients in chronic phase. Such a response was not found in the two patients with liver cirrhosis. Single-stranded conformation polymorphism (SSCP) and sequence analyses of HVR1 of E2 showed the lowest HVR1 heterogeneity in patients in acute phase and the highest one in those in chronic phase, while the long-time carriers of the virus showed an intermediate heterogeneity. This may reflect a specific interplay between the virus and immune system. The HVR1 heterogeneity may rise in the course of infection as a means of evading the immune pressure. Then, when an organism is unable to clear the virus, because the responses to HVR1 epitopes are weakened or exhausted, a population of less heterogeneous HVR1 variants may be established.

A novel c.C2754 > T transition in the androgen receptor gene introduces the premature termination codon Q798X and results in a truncated form of the receptor

A genetic analysis of a female with a 46,XY genotype and typical symptoms of the complete androgen insensitivity syndrome (CAIS) was conducted. The patient was diagnosed with an abdominal tumor due to the presence of a Sertoli cell adenoma in both gonads. Multiple temperature single-stranded conformational polymorphism (MSSCP) and sequence analyses of the androgen receptor gene revealed a c.C2754 > T mutation in exon 6. This mutation, which has not been previously reported, alters a Gln codon to a termination codon (Q798X). This results in the interruption of the amino acid sequence of the androgen receptor within the ligand-binding domain between helices VII and VIII. The truncated form of the receptor is devoid of 123 amino acids at the carboxyl end, a major part of the ligand-binding domain, and the AT2 sequence responsible for the activation of the transcription. It was concluded that the novel c.C2754 > T transition rendered the androgen receptor incapable of both ligand binding and activating the transcription, and was the cause of CAIS in the patient.