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PubMed · 8062328

[Androgen insensitivity].

Abstract

Manifestations of resistance to androgens vary within a wide range from an almost normal female phenotype to men whose only complaint is infertility. Insensitivity is caused by mutation of the gene for androgenic receptors, located on the X chromosome. Androgenic insensitivity is associated of all known hormonal resistances with the most varied mutational changes-some hundred of the latter were described. Mutations do not correlate with the clinical picture. Insensitivity to androgens is not necessarily associated with the inability of androgens to bind with the appropriate receptor, because mutations can affect any of the three receptor domains, i.e. not only the domain binding the ligand but also the domain by which the steroid receptor complex is linked to the DNA of the regulated gene or N-terminal, the so-called transactivation domain, responsible for the transfer of the hormone-borne signal to the initiation site of the controlled gene. Androgenic insensitivity can be associated with some tumourous diseases depending on steroid sex hormones such as prostate or breast cancer and also-as reported for the first time in this paper-e.g. with lymphogranuloma. Some neurodegerative diseases are also associated with a certain degree of androgenic insensitivity. For detection of androgenic resistance in addition to molecular genetic analysis dynamic tests were recommended which involve the follow-up of androgen-dependent indicators after androgen administration. These indicators are e.g. nitrogen retention or the SHBG level. The original modification of the SHBG test for androgen insensitivity is described.

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BibTeXRIS

L Stárka, R Hampl. 1994-06-27. [Androgen insensitivity].. https://pubmed.ncbi.nlm.nih.gov/8062328/

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Functional in vitro characterisation of the androgen receptor GGN polymorphism.

Superior androgen receptor (AR) function in subjects carrying a GGN repeat length of 23 (GGN23) has been indicated in vivo. Therefore, the activity of the AR carrying GGN23 combined with CAG22 was compared to the AR with GGN10, 24 and 27, respectively, in the presence of 0.1-100 nM testosterone or DHT. At 100 nM DHT, GGN24 showed 35% lower transactivating activity (95% [CI]: 20-50%) than GGN23. GGN10 and GGN27 also showed significantly less AR activity than GGN23 (mean differences [95% CI]: 54% [40-68%] and 58% [39-78%], respectively). The same trend was also observed at lower DHT concentrations. In response to R1881, GGN23 activity was significantly higher than for other lengths. ARs with other glutamine numbers than 23 have lower transactivating capacity in response to both testosterone and DHT. Congenital malformations and other signs of hypoandrogenism in subjects with AR gene GGN lengths other than 23 could, hence, be related to a lower AR activity.

Androgen-Insensitivity Syndrome↗

[Incomplete androgen insensitivity].

In the androgen insensitivity syndrome (AIS) the androgen effect is decreased in the fetus and the youth despite the adequate testosterone production. Usually the mutation of the androgen receptor is responsible for the disease. In the presented case the external genitalia were similar to female genitalia but masses were palpable in the labioscrotal fold. The karyotype was 46,XY. There was no increase in the testosterone level during the first three months of life. The stimulation test by stanazolol and the androgen receptor gene analysis verified the androgen insensitivity. The mutation was absent in the mother's leukocytes. This fact makes the genetic advising difficult in this family.

Androgen-Insensitivity Syndrome↗

Androgen receptor gene mutations in androgen insensitivity syndrome cause distinct patterns of reduced activation of androgen-responsive promoter constructs.

Assessment of quantitative impairment of reporter gene activation is an important strategy proving pathogenetic relevance of androgen receptor (AR)-gene mutations in androgen insensitivity syndrome (AIS). We hypothesized the additional existence of mutation-specific patterns of reduced target gene activation. Four AR-gene mutations causing AIS, L712F, M780I, R855H, and V866M, respectively, were recreated in an AR-expression plasmid. Activation of three structurally different androgen-dependent promoters (MMTV, (ARE)2TATA, and GRE-OCT) was measured in transfected CHO-cells in response to dihydrotestosterone (DHT), testosterone, androstenedione and stanozolol (S). V866M showed the lowest activity across all conditions. R855H exhibited strikingly high activation of MMTV in response to DHT. M780I showed markedly low activation of (ARE)2TATA by S. L712F demonstrated high activation of GRE-OCT. In essence, each mutation was characterized in this model by a specific pattern of reduced reporter gene activation. Our AR crystal structure analyses showed that L712 and M780 may cause distinct alterations of AR-ligand- and AR-coregulator interaction interfaces supporting the experimental observations. Our data support the hypothesis that mutations of the AR-gene in AIS induce mutation-specific patterns of reduced promoter activation in vitro. Considering the diversity of natural androgen-regulated promoters, mutation-specific differences of androgen response patterns may be of relevance in vivo and consequently may influence the AIS-phenotype. Assessment of transactivation patterns in vitro may be an interesting concept to extend functional description of AR-gene mutations in AIS.

Androgen-Insensitivity Syndrome↗