Genetic polymorphism of human aconitase

The aconitase isozymes of human tissues have been investigated using the method of starch gel electrophoresis and specific staining methods. Two sets of isozymes have been identified: ACON M is associated with the mitochondria, ACON S is cytoplasmic. Variant phenotypes of both forms have been identified in population surveys using placentae and white cells. Family studies and sib pair data derived from non identical twins indicate that the variants can be accounted for in terms of allelic variation at 2 independent autosomal loci ACON S and ACON M. Data from somatic cell hybrids indicate a probable assignment of ACON S to human chromosome 9 and ACON M to some other autosome. The ACON S locus is polymorphic in Black populations; 3 common alleles ACON S¹, ACON S² and ACON S⁴ have been discovered with frequencies of about 0.85, 0.03 and 0.12 respectively. In Europeans only rare variant alleles have been identified and their combined incidence as heterozygotes is about 1%. Variants of ACON M are rare and have been found so far only in Black populations with a frequency of about 1 in 250. Comparisons of the biochemical properties of the isozymes are in progress.