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D Smillie

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Journal Article↗

Association between MHC class II alleles and clearance of circulating hepatitis C virus. Members of the Trent Hepatitis C Virus Study Group.

The frequencies of HLA class I antigens and class II haplotypes were compared in subjects with previous (polymerase chain reaction [PCR]-negative) or with persistent (PCR-positive) hepatitis C virus (HCV) infection and in HCV patients with mild versus severe histologic activity scores on liver biopsy. The DRB1*11 allele group was found in 11 (31.4%) of 35 subjects with previous infection and in 11 (8.2%) of 135 subjects with persistent infection (P < .001). The DQB1*0301 allele was found in 18 (51.4%) of 35 subjects with previous infection and in 33 (24.4%) of 135 patients with persistent infection (P < .002). Both observations remained significant after correction for multiple testing. No significant association was shown between severity of disease and any HLA class I or II type. Thus, the HLA class II alleles DRB1*11 and DQB1*0301 are associated with clearance of circulating HCV.

Adult↗

A PCR-SSP method for detecting the His63Asp mutation in the HFE gene associated with hereditary haemochromatosis.

Hereditary haemochromatosis is an autosomal recessive disease in which there is defective regulation of iron absorption, causing gradual accumulation of excessive amounts of iron in certain organs. Recently, a candidate gene for hereditary haemochromatosis has been identified, located on the short arm of chromosome 6, telomeric to the major histocompatibility complex (MHC) and showing sequence homology to the human leucocyte antigen (HLA) class I genes. Two mutations have been found in this gene that are potential markers for haemochromatosis. The first, a cysteine to tyrosine substitution (Cys282Tyr) is strongly associated with the disease, whereas the second mutation, a histidine to aspartic acid substitution (His63Asp) shows a less obvious relation. To examine the importance of this second mutation in hereditary haemochromatosis it is important to study the links between this genotype and abnormalities of iron metabolism. A polymerase chain reaction method using sequence specific primers is described which might be useful for identifying those individuals carrying the mutation that encodes the His63Asp substitution, who might be at risk from a milder form of haemochromatosis.

Amino Acid Substitution↗

A PCR-SSP method for detecting the Cys282Tyr mutation in the HFE gene associated with hereditary haemochromatosis.

Hereditary haemochromatosis is a common genetic disorder that causes hyperabsorption of dietary iron, leading to increased deposition and various organic diseases. Early diagnosis is important if effective treatment is to be applied and the iron overload corrected before the onset of clinical symptoms. Recently, a candidate gene has been identified in which a single point mutation shows a very close association with hereditary haemochromatosis. A polymerase chain reaction method using sequence specific primers (PCR-SSP) is described that, in conjunction with a simple DNA extraction method, would provide a specific diagnostic test or rapid screening procedure for this putative haemochromatosis associated mutation.

Cysteine↗

An HLA-C-specific DNA probe.

Analysis of available nucleotide sequence data for class I HLA genes has established that the seventh intron is one of the gene regions which expresses the highest degree of locus specificity (the percentage sequence divergence between nonallelic genes minus the percentage sequence divergence between allelic genes). We have subcloned short DNA sequences including this region from the HLA-Cw3 gene. Two clones, pC250 and pC800, were tested by hybridizing them at high stringency to a panel of clones containing class I HLA genes. Under conditions permitting a strong hybridization signal with a C-locus gene, pC800 also expressed a weak but significant hybridization to other class I genes, while pC250 appeared to hybridize exclusively to the C-locus gene. Hybridization of the pC250 probe at high stringency to Hind III-digested genomic DNA from a panel of unrelated individuals and homozygous typing cell lines revealed a single band in all cases. However, equivalent hybridization against Eco RI-digested DNA revealed two hybridization bands, one at 7.9 kb which correlated with the serologically defined Cw5 and Cw8 alleles, and one at 7.6 kb which correlated with the Cw1, Cw2, Cw3, Cw4, Cw6, and Cw7 alleles.

Alleles↗