Browsing Anatomical Pathology by browse.metadata.advisor "De Villiers, J. N. P."
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- ItemAnalysis of hereditary haemochromatosis and clinical correlations in the elderly(Stellenbosch : Stellenbosch University, 2000-12) Bouwens, C. S. H.; Kotze, Maritha J.; Maritz, F. J.; De Villiers, J. N. P.; Stellenbosch University. Faculty of Medicine & Health Sciences. Dept. of Pathology.ENGLISH ABSTRACT: Hereditary haemochromatosis (HH) is an autosomal recessive iron storage disease where the accumulation of iron in parenchymal organs may lead to diabetes, heart failure, liver cirrhosis, arthropathy, weakness and a variety of other ailments if preventive measures are not taken. HH is often not considered as a cause of these conditions, particularly not in the elderly where the background frequencies of type II diabetes, osteoarthritis and heart failure are generally high. Heterozygosity for C282Y, the HFE-mutation causing HH in approximately 80% of affected individuals worldwide, has been linked to a raised incidence of malignancies of the colon and rectum, stomach and the haematological system. One of the highest carrier-frequencies (116) in the world for this mutation has been reported in the South-African Afrikaner population, resulting in C282Y-homozygosity in approximately 1 in every 115 people in this group. A sample of 197 elderly Afrikaner volunteers was recruited for genotype/phenotype association studies. Their clinical presentation was denoted, biochemical iron-status determined and HFE genotyping performed. Either an increase or decrease in survival, or both, were proposed, depending on possible gender effects. HH has been positively associated with various cancer types, but may also protect against iron-deficiency anaemia which is by far the most frequent cause of anaemia in the older person. This study has led to the following findings: 1. The carrier frequency of mutation C282Y was found to be 1/8 in the elderly population (similar in males and females), which is slightly lower than the 1/6 reported in younger adults from the same population. Only one C282Y homozygote and two C282YIH63D compound heterozygotes were detected, all of them female. 2. The prevalence of diabetes, heart disease, arthropathy or a combination of these conditions did not differ significantly in C282Y heterozygotes and the mutationnegative group. 3. Among 24 C282Y heterozygotes only one individual with rectal carcmoma was detected compared with two cases with rectal- and seven with colonic malignancies in 153 mutation-negative individuals. The single female C282Y homozygote identified suffered from both rectal and colon carcinoma and died approximately 6 months ago as a consequence of her colon malignancy. 4. Serum ferritin appears to be a highly unreliable parameter of iron status, particularly in the elderly where a variety of factors that may influence the levels are often present in elderly individuals. This may be due to ageing alone or as a result of multiple comorbidities. 5. Serum ferritin levels were lower than expected in elderly subjects with mutation C282Y and compound heterozygotes with both C282Y and H63D, which may be related to a variable penetrance of the HFE gene mutations. It is possible that variation in other genes exist that confer protection against iron-loading by gene-gene interaction. The probability that environmental factors (e.g. a low iron diet) are more important in this respect cannot be excluded, although this is considered less likely in the light of the fact that the same trend was observed in all mutation-positive elderly individuals. It is therefore highly likely that C282Y -positive subjects with significant iron loading have died before reaching their seventies, particularly since none of the males included in this study were homozygous or compound heterozygous for the mutations analysed. In conclusion, possession of a mutant HFE gene does not appear to confer a survival advantage in old age, neither does it seem that mutation carriers with significant ironloading are overlooked by the medical fraternity. Further investigations are warranted to shed more light on the contributions of gene-gene and gene-environment interaction in the clinical manifestation of Hll, and how these processes can be manipulated to prevent the symptoms of this largely underdiagnosed disease.