EVIDENCE OF GENETIC TRANSMISSION IN AFRICAN IRON OVERLOAD

Iron overload in Africa was previously regarded as purely due to exces sive iron in traditional beer, but we recently found evidence that tra nsferrin saturation and unsaturated iron binding capacity may be influ enced by an interaction between dietary iron content and a gene distin ct from any HLA-linked locus. To determine if serum ferritin follows a genetic pattern and to confirm our previous observations, we studied an additional 351 Zimbabweans and South Africans from 45 families rang ing in size from two to 54 members. Iron status was characterized with repeated morning measurements of serum ferritin, transferrin saturati on, and unsaturated iron binding capacity after supplementation with v itamin C. For each measure of iron status, segregation analysis was co nsistent with an interaction between a postulated iron-loading gene an d dietary iron content (P < .01). In the most likely model, transferri n saturation is 75% and serum ferritin is 985 mu g/L in a 40-year-old male heterozygote with an estimated beer consumption of 10,000 L, wher eas the saturation is 36% and serum ferritin is 233 mu g/L in an unaff ected individual with identical age, sex, and beer consumption, This s egregation analysis provides further evidence for a genetic influence on iron overload in Africans, (C) 1998 by The American Society of Hema tology.