20 - Divalent metal transporter-1 (SLC11A2) iron overload

Summary

Divalent metal transporter-1 (DMT1) is a member of the “natural-resistance-associated macrophage protein” (Nramp) family. DMT1 is upregulated by dietary iron deficiency, is expressed strongly on the microvillus membranes of duodenal enterocytes at the villus tips, and is a key mediator of iron absorption. DMT1 also mediates iron transfer from endosomes into the cytosol of developing erythroid cells. The SLC11A2 gene that encodes DMT1 is located on chromosome 12q13 (OMIM *604653).

In 1964, Shahidi and colleagues described a brother and sister of French-Canadian descent who had hypochromic, microcytic anemia. These siblings also had elevated serum iron concentrations, massive deposition of iron in hepatocytes, and absence of stainable iron in the bone marrow. These children apparently had no defect in transferrin or heme synthesis. Two of their siblings appeared to have normal iron phenotypes. In 2004 and 2005, Priwitzerova and colleagues described a Czech female in a consanguineous kinship who came to medical attention at age 3 months because she had a syndrome of abnormal iron metabolism characterized by severe hypochromic, microcytic anemia, erythroid hyperplasia, abnormal erythroid maturation, elevated serum iron concentration, normal to slightly increased serum ferritin level, and markedly increased serum transferrin receptor levels. In 2005, Mims and colleagues reported that this woman was homozygous for a mutation in SLC11A2.

Clinical description

Clinical observations in patients with two SLC11A2 mutations are limited. In one case, left ventricular hypertrophy was detected before birth, and birth weight was low. Pallor is presumed to have been present in all reported cases.