Genetic variation at apolipoprotein E locus in Ethiopia: an E5 variant actually corresponds to two different mutant alleles: e*5 (Glu212Lys) and e*5 (Gln204Lys; Cys112Arg).

A previous investigation on apolipoprotein E polymorphism in the Ethiopian population highlighted the presence of a further variant allele named e*5 in addition to the three common alleles. The variant is considered rare elsewhere but has a frequency of more than 1% in this population. Now characterized by gene sequencing and restriction isotyping in many members of the families of the originary carriers, the variant isoform has actually been found to be determined by two different gene mutations. Effectively rare in Ethiopians, one of the two, E5 (Gln204Lys, Cys112Arg), has never been described before. The other, E5 (Glu212Lys), previously described in a subject of Turkish origin, is present at the polymorphic level only in the Ethiopian population. No subjects bearing these variants had anomalous lipid or apolipoprotein patterns. In the course of the present investigation both have been found to occur as rare variants in the southern Italian population as well. The occurrence of the two variants in the populations of Ethiopia and of the Mediterranean basin could be explained by taking into account the relevant Caucasoid contribution to the Ethiopian gene pool.