DIFFERENTIAL SPLICING OF HUMAN ANDROGEN RECEPTOR PRE-MESSENGER-RNA INX-LINKED REIFENSTEIN SYNDROME, BECAUSE OF A DELETION INVOLVING A PUTATIVE BRANCH SITE

The analysis of the androgen receptor (AR) gene, mRNA, and protein in a subject with X-linked Reifenstein syndrome (partial androgen insensi tivity) is reported. The presence of two mature AR transcripts in geni tal skin fibroblasts of the patient is established, and, by reverse tr anscriptase-PCR and RNase transcription analysis, the wild-type transc ript and a transcript in which exon 3 sequences are absent without dis ruption of the translational reading frame are identified. Sequencing and hybridization analysis show a deletion of >6 kb in intron 2 of the human AR gene, starting 18 bp upstream of exon 3. The deletion includ es the putative branchpoint sequence (BPS) but not the acceptor splice site on the intron 2/exon 3 boundary. The deletion of the putative in tron 2 BPS results in 30% inhibition of wild-type splicing. The mutant transcript encodes an AR protein lacking the second zinc finger of th e DNA-binding domain. Western/immunoblotting analysis is used to show that the mutant AR protein is expressed in genital skin fibroblasts of the patient. The residual 10% wild-type transcript can be the result of the use of a cryptic BPS located 63 bp upstream of the intron 2/exo n 3 boundary of the mutant AR gene. The mutated AR protein has no tran scription-activating potential and does not influence the transactivat ing properties of the wild-type AR, as tested in cotransfection studie s. It is concluded that the partial androgen-insensitivity syndrome of this patient is the consequence of the limited amount of wild-type AR protein expressed in androgen target cells, resulting from the deleti on of the intron 2 putative BPS.