Osvaldo M. Mutchinick, Heidy R. Arrieta, Beatríz E. Sánchez, Jazmín Arteaga
National Institute of Medical Sciences and Nutrition Salvador Zubirán, Vasco de Quiroga 15, Delegación Tlalpan, 14000 México, D.F., México
Hereditary hemochromatosis (HH) is considered one of the most frequent genetic diseases in humans with a prevalence of 1 in 200 to 1 in 400 affected adults in diverse ethnic groups, particularly in those of Caucasian origin. The metabolic defect is characterised by an excess of iron in different body tissues. Skin dark pigmentation, diabetes mellitus and cardiac disorders frequently are the first symptoms. Other early manifestations are joint and abdominal pain. Lately liver fibrosis and cirrhosis are frequent findings. Neither the C282Y and H63D HFE gene mutation frequencies nor the HH prevalence are known for the Mexican population. The above and the apparently low prevalence of the disease in our country, prompted us to investigate the gene and genotype frequencies for the C282Y and H63D mutations in a sample of 13 patients, 204 healthy Indians from 2 different ethnic groups from the state of Chiapas and 200 Mexican mestizos blood donors attending our Institute. PCR amplified DNA samples of each subject, with commonly used primers, were treated with restriction enzymes RsaI and BclI to identify the presence of the C282Y and the H63D mutations respectively. Our results show that the C282Y mutation is very rare in the native populations mentioned, because no one of the 204 individuals carries the Y allele. Something similar occurred with the mestizo group studied. However, the mutant allele frequency for the H63D variant was of 1.5, 4.4% and 8.0% for the Tojolabales, Tzeltales and mestizo ethnic groups respectively. Regarding the 13 patients, 11 males and 2 females, 6 do not carry any of the mutations and of the remaining 7, 1 was homozygous for the C282Y mutation and 1 was heterozygous, 3 were compound heterozygous, and 2 CC/HD heterozygous. According to our results the prevalence of the C282Y mutation in the native ethnic groups and the mestizo population is very similar to the one observed in Asians and Africans, and significantly lower than that described in Caucasians of Northern Europe. The same happened with the D mutant allele frequency that was also significantly lower than that observed in Spaniards and Irish people (p< .001). The above may in part explain the low prevalence of HH found in Mexicans and the absence of both mutations in 6/13 patients with hemochromatosis suggests that other genes that participate in iron metabolism may be involved. We consider this last finding very interesting for further study other genes mutations probably not previously described.
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