Does the SLC40A1 gene modify HFE-related haemochromatosis phenotypes?

Most hereditary haemochromatosis patients are homozygous for the C282Y mutation of the HFE gene. However, the phenotypic expression and clinical aggressiveness of the disease differs considerably from patient to patient. The main objective of this work was to study the role of variants in the SLC40A1 gene in the severity of iron overload and his clinical consequences in 100 Spanish probands homozygous for the C282Y mutation of the HFE gene. We performed automated sequencing of the coding regions, including intron-exon junctions of the SLC40A1 gene. We studied the association between polymorphisms in the SLC40A1 gene and median values of iron removed, taking into account statistical corrections for multiple comparisons. No pathogenic mutations in the SLC40A1 were detected. Five known single nucleotide polymorphisms (SNPs) were identified, and two of them were associated with phenotypic characteristics. IVS1-24 C>G was associated with the amount of iron removed and presence of liver disease: Of the 83 patients finally studied for this SNP, the amount of iron removed was above the median in 36 of 56 (64.3%) for C/C, in nine of 23(39.1%) for C/G and in zero of four (0%) for G/G patients (P=0.01). Liver damage was observed in 34 of 56 patients (60.7%) for C/C, in eight of 23 (34.8%) for C/G and in zero of four (0%) for G/G (P=0.01). Both associations remained significant at multivariate analysis (P=0.011 and P=0.023, respectively). IVS1-24 C>G on the ferroportin gene seems to be a genetic modifier for clinical aggressiveness of HFE1 haemochromatosis.

Mutations in HAMP and HJV genes and their impact on expression of clinical hemochromatosis in a cohort of 100 Spanish patients homozygous for the C282Y mutation of HFE gene.

Most hereditary hemochromatosis (HH) patients are homozygous for the C282Y mutation of the HFE gene. Nevertheless, penetrance of the disease is very variable. In some patients, penetrance can be mediated by concomitant mutations in other iron master genes. We evaluated the clinical impact of hepcidin (HAMP) and hemojuvelin mutations in a cohort of 100 Spanish patients homozygous for the C282Y mutation of the HFE gene. HAMP and hemojuvelin mutations were evaluated in all patients by bidirectional direct cycle sequencing. Phenotype-genotype interactions were evaluated. A heterozygous mutation of the HAMP gene (G71D) was found in only one out of 100 cases. Following, we performed a study of several members of that family, and we observed several members had a digenic inheritance of the C282Y mutation of the HFE gene and the G71D mutation of the HAMP gene. This mutation in the HAMP gene did not modify the phenotype of the individuals who were homozygous for the C282Y mutation. One other patient presented a new polymorphism in the hemojuvelin gene, without consequences in iron load or clinical course of the disease. In conclusion, HAMP and hemojuvelin mutations are rare among Spanish HH patients, and their impact in this population is not significant.

Secondary coenzyme Q10 deficiencies in oxidative phosphorylation (OXPHOS) and non-OXPHOS disorders.

We evaluated the coenzyme Q10 (CoQ) levels in patients who were diagnosed with mitochondrial oxidative phosphorylation (OXPHOS) and non-OXPHOS disorders (n=72). Data from the 72 cases in this study revealed that 44.4% of patients showed low CoQ concentrations in either their skeletal muscle or skin fibroblasts. Our findings suggest that secondary CoQ deficiency is a common finding in OXPHOS and non-OXPHOS disorders. We hypothesize that cases of CoQ deficiency associated with OXPHOS defects could be an adaptive mechanism to maintain a balanced OXPHOS, although the mechanisms explaining these deficiencies and the pathophysiological role of secondary CoQ deficiency deserves further investigation.

Prevalence of the C282Y, H63D, and S65C mutations of the HFE gene in 1,146 newborns from a region of Northern Spain.

In Spain, 85% of patients with genetic hemochromatosis (GH) are homozygous for the C282Y mutation of the HFE gene. H63D and S65C mutations of HFE may also play some role in the disease. The aim of this study was to establish the prevalence of C282Y, H63D, and S65C mutations of the HFE gene in newborns in Catalonia, Spain. One thousand one hundred forty-six newborn screening cards were selected randomly. DNA from these cards was extracted and HFE mutations were analyzed with the LightCycler equipment (Roche Diagnostics Gmbh, Mannheim, Germany). Sufficient DNA sample was obtained to screen for the three mutations in 1,043 cases (91%). The allelic frequencies of C282Y, H63D, and S65C mutations were 0.03 (IC 95% 0.022-0.037), 0.2 (IC 95% 0.19-0.22), and 0.01 (95% confidence interval [CI] 0.006-0.015), respectively. The frequency of C282Y homozygous newborns was 0.001 (95% CI 0.0005-0.0014). The frequencies of newborns doubly heterozygous for C282Y/H63D and C282Y/S65C were 0.01 (95% CI 0.005-0.02) and 0.002 (95% CI 0.0002-0.01), respectively. The allelic frequency of C282Y mutation is similar to that observed in Southern France, in the Czech Republic and in some areas of Italy. The allelic frequency of H63D mutation in Catalonia is the highest reported to date. Nevertheless, S65C is infrequent. These data should be kept in mind when designing hemochromatosis genotypic screening programs in Catalonia.

The relationship between iron overload and clinical characteristics in a Spanish cohort of 100 C282Y homozygous hemochromatosis patients.

We studied the relationship between iron removed by venesection, sex, age, and clinical characteristics in a group of 100 Spanish probands with hereditary hemochromatosis (HH), all C282Y homozygous in the HFE gene. Iron overload was higher in men than in women (P < 0.0001) and increased with age (P = 0.02). Forty-four patients presented with liver disease (28 had fibrosis-cirrhosis of the liver), 24 with diabetes, 18 with arthropathy, and 13/73 men with impotence. No clinical consequences of hemochromatosis were observed in 43 patients. The number of clinical complications was higher in men (P = 0.01) and increased with age (P = 0.006) and with the amount of iron removed (P < 0.0001). The amount of iron removed was significantly higher by univariate analysis in patients with liver disease (P < 0.0001), diabetes (P = 0.007), arthropathy (P = 0.006), and impotence (P = 0.003) than in patients without these complications. In the multivariant analysis, only liver disease maintained a significant relationship with the amount of iron removed (P < 0.0001). Diabetes and arthropathy were closely related with previous liver disease, and impotence appeared mainly in hemochromatosic men with diabetes and alcoholism.