Are homozygous Apo-AIM mutations lethal?
In addition, AiG claims that since only heterozygotes of the Apo-AIM mutation have been identified so far, “This may suggest that the homozygote (both genes the same) A-I Milano mutation is lethal.” Contrary to AiG’s claim, this finding is unsurprising given the present rarity of the Milano mutation. The early work studying the heterozygous carriers of this mutant allele identified only 33 individuals, after genetic testing of all inhabitants in an isolated northern Italian village (about 1000 people, 15). In the gene pool of this village, where the mutant allele originated and which has an extremely high concentration of Apo-AIM mutants relative to other human populations, the Milano allele has a frequency of only 1.65% (33 mutant alleles out of 2000 total alleles of this gene). Assuming that those individuals are mating randomly, it would be somewhat surprising to find a homozygous individual in a population of 1000 since we expect to find a homozygote at a frequency of about 1/3700
