Study on the genetic mutations of 17 alpha-hydroxylase/17,20-lyase deficiency in Chinese patients.
OBJECTIVE
To investigate the CYP17A1 gene mutations in Chinese patients with 17 alpha-hydroxylase/17, 20-lyase deficiency.


METHODS
Clinical data were retrospectively analyzed. The CYP17A1 gene mutations were detected in 5 cases with 17 alpha-hydroxylase/17, 20-lyase deficiency and their relatives. The genomic DNA of the patients was isolated from whole blood. Seven pairs of primers were used to amplify eight exons and exon-intron boundaries of the CYP17A1 gene. The amplified PCR products were purified by agarose gel and then directly sequenced. In order to confirm the DNA sequences of different alleles, some fragments were inserted into pMD 18-T vector and then sequenced. Sequencing results were compared to the established human CYP17A1 sequence.


RESULTS
Briefly, we found 2 kinds of compound mutations, of which were: (1) 6436-6438(TAC-->AA), causing amino acid Y329K, 418X; (2) 6531-6532(GC-->A), causing amino acid L361F, 418X. Among the five cases, four were homozygous for 6436-6438(TAC-->AA), whereas one was compound heterozygous for 6436-6438(TAC-->AA)/6531-6532(GC-->A). The clinical characteristics of 5 cases were all completely combined defects of 17 alpha-hydroxylase/17, 20-lyase, and they all carried two alleles of CYP17A1 gene mutations that all shifted the reading frame and resulted in truncated protein which lack of the activity center site of P450C17, of which corresponding with their clinical feature.


CONCLUSIONS
Nine alleles have the mutation of 6436-6438(TAC-->AA), accounting for 90% of total alleles (9/10). That suggests this kind of mutation may have racial specificity. More study should be done to have better understanding of the function of the truncated P450C17 enzymes.
Tao
Hong
H
Department of Comprehensive Medicine, Beijing Anzhen Hospital, Capital University of Medical Sciences, Beijing, 100029 P.R.China. vivientao@yahoo.com
Lu
Zhao-lin
ZL
Zhang
Bo
B
Mi
Shu-hua
SH
Wang
Nan-ye
NY
Wang
Xi-zhi
XZ
Wu
Jin
J
D000293:Adolescent; D000312:Adrenal Hyperplasia, Congenital / Q000201:enzymology / Q000235:genetics*; D000483:Alleles; D044466:Asian People / Q000235:genetics*; D001483:Base Sequence; D004247:DNA; D004252:DNA Mutational Analysis; D017931:DNA Primers; D005091:Exons / Q000235:genetics; D006801:Humans; D008297:Male; D008969:Molecular Sequence Data; D009154:Mutation; D017354:Point Mutation; D016133:Polymerase Chain Reaction; D050035:Sexual Infantilism / Q000235:genetics*; D013254:Steroid 17-alpha-Hydroxylase / Q000235:genetics* / Q000378:metabolism; D055815:Young Adult
D017931:DNA Primers; D004247:DNA; C501892:CYP17A1 protein, human; D013254:Steroid 17-alpha-Hydroxylase