title: CYP17A1 intron mutation causing cryptic splicing in 17α-hydroxylase deficiency.
abstract: 17α-Hydroxylase/17, 20-lyase deficiency (17OHD) is an autosomal recessive disease causing congenital adrenal hyperplasia and a rare cause of hypertension with hypokalemia. The CYP17A1 gene mutation leads to 17OHD and its clinical features. We described an 18 y/o female with clinical features of 17α-hydroxylase/17, 20-lyase deficiency and characterized the functional consequences of an intronic CYP17A1 mutation. The coding regions and flanking intronic bases of the CYP17A1 gene were amplified by PCR and sequenced. The patient is a compound heterozygote for the previously described p.R358X and IVS1 +2T>C mutations. A first intron splice donor site mutation was re-created in minigene and full-length expression vectors. Pre-mRNA splicing of the variant CYP17A1 intron was studied in transfected cells and in a transformed lymphoblastoid cell line. When the full-length CYP17A1 gene and minigene containing the intronic mutation was expressed in transfected cells, the majority (>90%) of mRNA transcripts were incorrectly spliced. Only the p.R358X transcript was detected in the EBV-transformed lymphoblastoid cell line. The IVS1 +2T>C mutation abolished most 17α-hydroxylase/17, 20-lyase enzyme activity by aberrant mRNA splicing to an intronic pseudo-exon, causing a frame shift and early termination.
authors.affiliation: Division of Nephrology, Department of Medicine, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan.
authors.forename: Daw-Yang
authors.initials: DY
authors.lastname: Hwang
authors.forename: Chi-Chih
authors.initials: CC
authors.lastname: Hung
authors.forename: Felix G
authors.initials: FG
authors.lastname: Riepe
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Auchus
authors.forename: Alexandra E
authors.initials: AE
authors.lastname: Kulle
authors.forename: Paul-Martin
authors.initials: PM
authors.lastname: Holterhus
authors.forename: Mei-Chyn
authors.initials: MC
authors.lastname: Chao
authors.forename: Mei-Chuan
authors.initials: MC
authors.lastname: Kuo
authors.forename: Shang-Jyh
authors.initials: SJ
authors.lastname: Hwang
authors.forename: Hung-Chun
authors.initials: HC
authors.lastname: Chen
mesh_terms: D000293:Adolescent; D000818:Animals; D015153:Blotting, Western; D019556:COS Cells; D002460:Cell Line; D002522:Chlorocebus aethiops; D005260:Female; D006801:Humans; D007438:Introns / Q000235:genetics*; D009154:Mutation; D012326:RNA Splicing / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013254:Steroid 17-alpha-Hydroxylase / Q000235:genetics* / Q000378:metabolism*
chemical_list: C501892:CYP17A1 protein, human; D013254:Steroid 17-alpha-Hydroxylase