Clinical and genetic analysis of 14 cases with 21-hydroxylase deficiency

Abstract

Objective To analyze the correlation of clinical phenotype and genotype and gene mutation frequency characteristics of 21-hydroxylase deficiency, and to provide the basis for clinical diagnosis and methods for early intervention. Methods The clinical phenotypic signs and examination results of 14 cases with 21-hydroxylase deficiency were collected from September 2008 to December 2016 in Children′s Hospital of Shanxi Province.Point mutations, deletions and conversion mutations for gene CYP21A2 coding 21-hydroxylase were detected through using next generation sequencing(NGS) and multiplex ligation-dependent probe amplification(MLPA). The captured mutations were further confirmed with Sanger sequencing.Furthermore, the family members underwent the co-segregation validation through the Sanger sequencing or MLPA in those captured mutated sites. Results Among the total 14 cases, 9 cases were identified as the salt wasting, 5 cases the simple virilizing; 10 cases of compound heterozygous mutations, and 4 cases of homozygous mutations.Analysis of the 14 patients revealed 8 different kinds of mutations in CYP21A2 gene.The most frequent mutations of CYP21A2 gene were I2G [50%(14/28)] and I173N [21.4%(6/28)], followed by Arg357Trp[10.7%(3/28)]. Del[10.7%(3/28)] mutations including E247fs, Gly111fs and R484fs.Q319X[3.6%(1/28)] and Arg355His[3.6%(1/28)] were rarely found.Missense mutation was found in 10 cases, splicing mutation in 14 cases, frameshift mutations in 3 cases, nonsense mutations in 1 case.All of the mutations were inherited from their parents, and no new mutation was found.The most common mutations for salt wasting and simple virilizing were respectively I2G[50%(9/18)] and I173N [50%(5/10)]. Collectively, genotypes and phenotypes were matched with each other. Conclusions The combination of clinical phenotypes with laboratory examination by gene sequencing and comprehensive analysis, is helpful to early diagnosis, differential diagnosis and optimized treatment, which will improve prognosis and provide guidance for genetic consultancy. Key words: Congenital adrenal hyperplasia; 21-hydroxylase; Mutation; Next generation sequencing