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Mutation analysis of the HLA-H gene in Italian hemochromatosis (haemochromatosis) patients
IRCCS CSS San Giovanni Rotondo, Foggia, Italy.
Hemochromatosis (HH) is an inborn error of iron metabolism, frequent among Caucasians, characterized by progressive iron loading that, if untreated, causes high morbidity and death. HLA-H, a putative HH gene, has recently been isolated. The large majority of patients so far studied are homozygous for a single mutation, which results in a cysteine-to-tyrosine substitution at amino acid 282 of the protein. A second, less frequent, variant, His63Asp, has an undefined role in the pathogenesis of the disease. Here we report that the Cys282Tyr change accounts for 69% of HH chromosomes in a series of 75 unrelated Italian patients who fulfilled well-defined criteria for HH diagnosis. Sixty-four percent of patients were Cys282Tyr homozygous, 10% were heterozygous, and 21% carried the normal allele. The same mutation was rare in normal controls. The His63Asp variant was less frequent but had a similar frequency among affected and normal chromosomes. Subjects without two copies of the Cys282Tyr change were both isolated patients and individuals from families with a 6p-linked disease. Mutation analysis of the HLA-H gene, carried out by RNA-SSCP in the latter patients, did not reveal any significant nucleotide abnormality in coding sequences and intron-exon boundaries. The absence of mutations in HLA-H gene was confirmed in three cases by direct sequencing. Major deletions or rearrangements of the gene were excluded by Southern blotting. The existence of patients with clinical and histological features of HH, but without mutations in HLA-H gene, suggests that in Italy the disease is more heterogeneous than reported in northern Europe.
Haemochromatosis gene mutations in a clustered Italian population: evidence of high prevalence in people of Celtic ancestry
Gabriele Pozzato1, Francesca Zorat1, Fabiana Nascimben1, Michela Gregorutti1, Consuelo Comar1, Stefano Baracetti1, Serena Vatta2, Elena Bevilacqua3, Anna Belgrano3, Sergio Crovella3 and Antonio Amoroso2,3
Hereditary haemochromatosis is an inherited disorder characterised by an excessive iron absorption from the diet and is associated with several HFE gene mutations. One hypothesis is that these genetic mutations originated in the Celtic populations. The aim of this study is to determine the frequency of HFE gene mutations in a clustered Italian population of Celtic ancestry (Cimbri, Asiago plateau). One hundred and forty-nine consecutive unrelated blood donors (31 females and 118 males) were enrolled in this study. A family investigation was performed in each case to identify the ethnic origin of the individuals. The analysis of HFE gene mutations was performed by PCR amplification followed by digestion with RsaI and DpnII restriction enzymes. At least one HFE gene mutation was identified in 49 individuals (32.9%) of the studied population. The allele frequencies of the C282Y and H63D were respectively 0.037 and 0.144. When we considered only the 103 individuals with relatives born in Asiago, the prevalence of the HFE mutations rose from 32.9 to 39.8%; the allele frequencies of the C282Y and H63D were respectively 0.048 and 0.174. The mean serum iron and ferritin levels were significantly higher in individuals with the HFE mutations than in normal cases. This study indicates that the prevalence of the HFE gene mutations is surprisingly high in Italians with Celtic ancestry. This could suggest the need to perform large mass studies in selected areas of the country to detect the affected patients and prevent the disease in homozygous individuals. European Journal of Human Genetics (2001) 9, 445-451.