High frequency of Q318X mutation in patients with congenital adrenal hyperplasia due to 21-hydroxylase deficiency in northeast Brazil.
OBJECTIVE
Deficiency of 21-hydroxylase is the most common form of congenital adrenal hyperplasia (CAH-21OH). The aim of this study was to determine, by allele-specific PCR, the frequency of microconversions of the CYP21A2, in sixteen patients with the classical forms and in 5 patients with the nonclassical (NC) form of CAH-21OH and correlate genotype with phenotype.


METHODS
Genotypes were classified into 3 mutation groups (A, B and C), based on the degree of enzymatic activity. Screening for 7 microconversions by allele-specific PCR diagnosed 74.3% (n=26) of the 35 unrelated alleles.


RESULTS
The most frequent mutations were Q318X (25.7%), V281L (17.1%), I2 Splice (14.3%), I172N (14.3%), and R356W (14.3%). Genotype was identified in 57.1% of the patients. We observed correlation between genotype and phenotype in 91.7% of the cases.


CONCLUSIONS
The highest frequency for Q318X (25.7%) when compared to other studies may reflect individual sample variations in this Northeastern population.
Division of Endocrinology, Federal University of Sergipe, Aracaju, SE, Brazil. vivilaser@gmail.com
Viviane C
VC
Campos
Rossana M C
RM
Pereira
Natália
N
Torres
Margaret de
Md
Castro
Manuel H
MH
Aguiar-Oliveira
D000293:Adolescent; D000312:Adrenal Hyperplasia, Congenital / Q000145:classification / Q000235:genetics*; D001938:Brazil; D002675:Child, Preschool; D005260:Female; D005787:Gene Frequency / Q000235:genetics*; D005838:Genotype; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D009154:Mutation / Q000235:genetics*; D010641:Phenotype; D013255:Steroid 21-Hydroxylase / Q000235:genetics*
C531510:CYP21A2 protein, human; D013255:Steroid 21-Hydroxylase