Human Complete Androgen Insensitivity with Normal Dihydrotestosterone Receptor Binding Capacity in Cultured Genital Skin Fibroblasts: Evidence for a Qualitative Abnormality of the Receptor*
TERRY R. BROWN,
MARC MAES,
STEPHEN W. ROTHWELL and
CLAUDE J. MIGEON
Department of Pediatrics, Division ofPediatric Endocrinology, The Johns Hopkins University School of Medicine Baltimore, Maryland 21205
Address all correspondence and requests for reprints to: Dr. Terry R. Brown, Department of Pediatrics, Division of Pediatric Endocrinology, CMSC 3-110, The Johns Hopkins Hospital, Baltimore, Maryland 21205.
Complete androgen insensitivity syndrome (CAIS), or so-calledtesticular feminization, results from the lack of androgen actionon target organs. Within this syndrome, two major variants havebeen described. In the first variant, the specific intracellularandrogen receptors are undetectable (CAIS, AR), whereas normallevels of androgen receptors are measured in the second variant(CAIS, AR+). From studies with cultured labial skin fibroblastsof three CAIS, AR+ patients from the same family, we have demonstratedthat their androgen receptors present qualitative differenceswhen compared to normal receptors: 1) the apparent affinityconstant (Kd) of 5dihydrotestosterone for the receptor is higherthan normal; 2) the in vitro dissociation rate of the receptor-steroidcomplex is faster than normal: 3) the cellular androgen receptoris more thermolabile than normal when cells are exposed to superphysiologicaltemperatures; and 4) the relative binding affinity of the androgenreceptor for progesterone is greater than normal. These findingssuggest the presence of a structural abnormality of the androgenreceptor in patients with CAIS, AR+. However, these changes(e.g. slightly decreased affinity of the receptor for 5a-dihydrotestosterone)probably do not explain the total lack of androgen action inthese patients. Finally, the present data from this family alongwith those from the literature suggest the presence of heterogeneityas to the cause of the defect in CAIS, AR+.
* This work was supported by USPHS Research Grant AM-00180, TraineeshipGrant T32-AM-07116, and Research Career Award 5-KO6- AM-21855(to C.J.M.). Presented in part at the 63rd Annual Meeting TheEndocrine Society, Cincinnati, OH, June 17-19,1981.
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