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.
ABSTRACT
<p><b>OBJECTIVE</b>To determine the type and frequency of phenylalanine hydroxylase gene (PAH) mutations in ethnic Hui patients from Ningxia with phenylketonuria (PKU).</p><p><b>METHODS</b>For 35 PKU children patients and 50 healthy individuals, all exons and promoters of the PAH gene were analyzed with PCR and direct sequencing.</p><p><b>RESULTS</b>Twenty mutations, including 8 missense mutations (40%), 5 nonsense mutations (25%), 4 splice site mutations (20%) and 3 deletion mutants (15%) were discovered. The overall detection rate was 68.57% (48/70). Common mutations have included R243Q (12.86%), R241C (11.43%), EX6-96A to G (5.71%), Y356X (5.71%), R413P(4.29%) and Q232X(4.29%), whilst rarer ones have included S16fsX10 (2.86%), R111X (2.86%) and L430P (2.86%). Among these, S16fsX10, L430P, D222G and IVS11+ 1G to A have not been reported previously. Y414X and S303fsX38 have not been reported in Hui ethnic group. No mutation was detected in the 50 normal controls.</p><p><b>CONCLUSION</b>The types and distribution of PAH gene mutations in ethnic Hui from Ningxia have been different from other areas of China. The mutations also showed a rich diversity.</p>