Exon Mutation Analysis Of Wilson Disease

Hepatolenticular degeneration (HLD) is an autosomal recessive disorder of copper transport that is characterized by accumulation of copper in the body. The worldwide prevalence of the disease is estimated in the order of 3-10 per 1 million, with a gene frequency of 0.56% and a carrier frequency of 1 in 90.The symptoms of HLD are due to copper-induced injury in these various organs, and the clinical manifestations are variable. Therefore it's difficult to diagnose HLD earlier. At present, study indicate that diagnose depend on gene analysis will much more help to early diagnose. The study for HLD gene mutation will make academic base for genie diagnose.The HLD gene is mapped on 13ql4.3, and the cDNA sequence has 4398 bp. This gene contains 21 exons and 20 introns. The length of exons ranged from 77bp to 1234bp, mostly about 200bp. 1465 amino acids havebeen coded. The protein product belongs to the group of cation-transporting p-type ATPase (ATP7B). This p-type ATPase has three domains. First is metal binding site domain, including six copper-binding sites, which is in the N-termmal segment of HLD gene product. Second is the functional domain of p-type ATPase, including phosphotrse domain, phosphorylation domain and ATP binding domain. The third one is transmembrane domain.Mutation screening in HLD patients led so far to detect 225 specific mutations, some of which appear to be population specific and some common to many populations. There are 144 missense, nonsense or silent mutations, 49 small deletions. 12 small insertions, 3 regulatory, 1 small indels, 11 splicing, 2 complex rearrangements and 3 gross deletions. The H1070Q mutation has been previously detected in populations of European ancestry, where it accounts for about 30% of the HLD chromosomes. Mutation of the yellow ethnic group HLD hasn't been screened integrality so far. This study reports the results of mutation screening carried out in HLD patients of the Han nationality in Zhejiang.Part I: Screening of the exon mutation in HLD patients ObjectiveTo investigate the types, distributing and frequency of the exon mutationin HLD patientsMethodThis study includes 30 HLD patients, a total of 60 HLD chromosomes.All of these chromosomes are of the Han nationality in Zhejiang. Thediagnosis of HLD is based on low caeruloplasmin and copper serum levels, high urinary copper excretion, and high hepatic copper content. DNA extraction and PCR are carried out by standard methods. Mutation detection is performed by direct sequencing of the exons as described in previous papers. ResultsWe identify 12 mutations of which 5 are novel. Of ihese mutations, 8 are missense, 2 are silent and 2 are regulatory mutation. 11 of these mutations are nucleotide substitutions and 1 is small deletion. The missense mutations D96G, D196E, S406A, V456L, R778L, K832R, P992L and V1216M occur in exon 2, 2, 2, 3, 8, 10, 13 and 17. The silent mutations, L770L and S1166S occur in exon 8 and 16. -123_-119delCGCCG and -75A>C occur in the regulatory area. 6 of these mutations are common to these population, 1216T>G 26.7%, 1366G>C 23.3%, 2310C>G28.3%, 2333G>T 28.3%, 2495A>G 25.0%, 2975C>T 26.7% and others are dispersed. ConclusionWe found 5 novel mutations in the Han nationality in Zhejiang. The rule of mutations in this population is difference from the populations of European.Part II: Relativity study of the genotype and phenotype ofHLD gene ObjectiveTo investigate the relativity of the genotype and phenotype of HLD gene.MethodCollecting the clinical information, including sex, age of onset,presentation, of these 30 HLD patients of the Han nationality in Zhejiangand compare it to the genotype.ResultsThere are 15 boys and 15 girls in this study, aged 4-14 years, average8.96±1.87 years. 18 of these are hepatic type, 8 are neurologic type and4 are other types. Each genotype has several phenotypes and all of theonset ages.ConclusionWe didn't find consanguineous relativity in genotype and phenotyp...