Androgen insensitivity in man: evidence for genetic heterogeneity.

Abstract

We have studied ten phenotypically similar patients with complete androgen insensitivity. All of the patients tested had significantly elevated serum luteinizing hormone and plasma androgens within or above the normal adult male range. On the basis of s ecific dihydrotestosterone binding by skin fibroblasts, we identified two subgroups. Six patients from five different families had undetectable dihydrotestosterone binding, while four patients from two families had normal binding activity. Our results indicate that within the clinical syndrome of androgen insensitivity there are at least two distinct genetic variants. These variants may result from allelic mutations of the same X-linked gene specifying the dihydrotestosterone receptor or, alternatively, from mutations of separate genes both being essential for androgen action in responsive cells.Recently we reported the presence of a receptor protein specific for dihydrotestosterone (DHT) in the cytoplasm and nucleus of cultured human skin fibroblasts (1, 2). In contrast, cells from two male siblings with complete androgen insensitivity syndrome (AIS) showed no detectable specific D4T binding (2, 3). The androgen insensitivity in this family apparently resulted from a mutation of an X-linked gene specifying the DHT receptor (3).In order to determine whether other patients with this clinical syndrome demonstrate a similar defect in androgen binding, we have studied additional patients with the AIS phenotype. On the basis of the DHT binding characteristics of their fibroblasts, two distinct groups were identified, those with undetectable DHT binding and those with normal androgen binding activity. These findings suggest that there is genetic heterogeneity among patients with androgen insensitivity. MATERIALS AND METHODSSubjects. Ten subjects with complete AIS were studied. Subjects no. 1 and 2 are nonidentical twins who were previously reported to have absent DHT binding activity in their skin fibroblasts (2). Subject no. 5, described by Wilkins (4), had a similarly affected sibling. Subjects no. 7, 8, and 9 (individuals IV-2, IV-4, and IV-10 in Fig. 1) are from a family described in detail elsewhere (5, 6). The pedigree shown in Fig. 1 has been revised from that previously reported (6). The remaining four subjects were sporadic cases with no family history of similar disorder.All Whole cell DHT binding was measured as previously reported (1, 2). Confluent monolayers of fibroblasts in 100 mm petri dishes were incubated for 20 min at 370 with [3H]DHT (0.2 to 1.5 X 10-9 M) dissolved in minimal essential medium without fetal calf serum. After incubation, the cells were harvested using 0.25% trypsin and washed at 40 in Tris-sucrose buffer (0.02 M Tris-HCl, pH 7.5, 0.32 M sucrose, 1 mM MgCl2) containing 1 mg/ml of bovine gammaglobulin. All subsequent procedures were carried out at 4°. After centrifugation at 800 X g for 15 min, the cells were suspended in 1.0 ml of Tris-KCl buffer (0.02 M Tris-HCl, pH 7.5, 0.5 M KC1, 1.5 mM EDTA) and lysed in an ultrasonic clean...

Impaired stimulation of 25-hydroxyvitamin D-24-hydroxylase in fibroblasts from a patient with vitamin D-dependent rickets, type II. A form of receptor-positive resistance to 1,25-dihydroxyvitamin D3.

“…Absent binding, decreased amount of receptor, and a qualitatively abnormal receptor are defects commonly seen in these glucocorticoid-resistant cells, while the inability to identify a receptor abnormality is rare (22)(23)(24)(25). Amrhein et al (26) were the first to report the presence of normal androgen receptor binding in a family with testicular feminization and to raise the possibility of a postreceptor defect in androgen action. However, when more sensitive techniques were developed to assess qualitative abnormalities of the androgen receptor, only a small fraction of the families with androgen resistance had no identifiable receptor abnormality (27).…”

“…However, when more sensitive techniques were developed to assess qualitative abnormalities of the androgen receptor, only a small fraction of the families with androgen resistance had no identifiable receptor abnormality (27). And, in fact, the first family reported to have receptor-positive androgen resistance (26) has recently been shown to have a qualitatively abnormal androgen receptor (28). Thus, defects in steroid hormone action at a postreceptor site are uncommon.…”

Differences in proteins synthesized by fibroblasts from normal individuals and patients with complete testicular feminization.

“…It is therefore possible that the 85-and 45-K proteins represent a part of the androgen receptor complex, the levels of which are <10% of those in normal fibroblasts. The possibility that the 85-and 45-K proteins are subunits of the androgen receptor is open to investigation in several ways, including analysis of proteins synthesized by fibroblasts from those more unusual patients, who show androgen insensitivity despite apparently normal receptor levels assessed by androgen binding in vitro (4). Studies addressed to this possibility are currently in progress.…”

“…This androgen-insensitive form of male pseudohermaphroditism has subsequently been shown to be due to an abnormality in androgen receptor activity (3). Two distinct forms of such patients have been described by Amrhein et al (4) on the basis of the binding of dihydrotestosterone (DHT)' to cultured fibroblasts from these patients: one type of patient has little or no cytosol binding activity while the other apparently has normal cytosol and nuclear binding.…”

Familial Incomplete Male Pseudohermaphroditism Associated with Impaired Nuclear Androgen Retention. STUDIES IN CULTURED SKIN FIBROBLASTS

“…Prior to this report, studies with cultured fibroblasts have revealed androgen resistance variants that are receptor-negative, receptor-deficient, and receptordefective (receptors that are thermolabile or are not stabilized by sodium molybdate) as well as receptor positive (4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(24)(25)(26)(27)(28)(29)(30)(31). Others have examined nuclear [3H]DHT uptake in fibroblasts from several patients with androgen resistance whose fibroblast whole cell…”