Characteristics of phenylalanine hydroxylase gene mutation in patients with phenylketonuria in Ningxia area / 中华围产医学杂志

ABSTRACT

Objective To characterize the mutation of phenylalanine hydroxylase (PAH) gene in patients with phenylketonuria(PKU) in Ningxia area,China.Methods Seventy-three children diagnosed with PKU at the Child and Maternal Healthcare Hospital of Ningxia Hui Autonomous Region between January 2010 and June 2013,and 100 non-PKU children randomly chosen from children with normal results in PKU screening were enrolled in the study.Venous blood was collected and the PAH gene sequence was determined by direct DNA sequencing after amplification with the polymerase chain reaction technique.The new gene mutations were defined based on the national and international literature search and databases.The source of the newly discovered mutations was also measured by examining and sequencing the blood samples of their parents.The Chi-square test was used for statistical analysis.Results Among 146 alleles of the 73 PKU children,the detection rate of mutation of PAH gene was 79.5％ (116/146),including 37 types of mutations occurring in 11 exons other than exon 2 and exon 13.The 37 different mutations included 22 missense mutations (59.5％,22/37),six nonsense mutations(16.2％,6/37),six splice site mutations(16.2％,6/37) and three deletion mutations(8.1％,3/37).p.R243Q(17.1％,25/146),EX6-96A ＞ G (6.8％,10/146),p.R241C(6.2％,9/146),p.R413P (5.5％,8/146),p.Rl11X(4.8％,7/146) and IVS4-1G ＞ A(4.8％,7/146) were found to have a higher mutation frequency.Meanwhile,p.R243Q was the most common mutation among Han and Hui ethnic groups with a frequency of 18.8％(12/64) and 15.9％ (13/82),respectively.In contrast,p.R241C showed a significant higher frequency in the Hui group [9.8％(8/82) vs 1.6％(1/64),x2=4.17,P=0.04].Four new mutations of PAH genes,including p.Q304K,p.H107R,p.F392I and p.N223I,were discovered after literature search and comparative studies.Conclusions PAH gene mutations in children with PKU in Ningxia area are unique and are characterized by the diversity and complexity of mutation occurrence in this ethnic region.