Rs4340

rs4340 is one of four SNPs representing perhaps the best studied ACE SNP. It is actually not a single nucleotide polymorphism at all; instead, it is an insertion/deletion of an Alu repetitive element in an intron of the ACE gene. Alleles containing the insertion are called "I" alleles, and "D" alleles lack the repetitive element. The other dbSNP entries all tagging this same single insertion/deletion SNP are:


 * rs1799752
 * rs13447447
 * rs4646994

There are numerous association studies reported for these SNPs. Examples:


 * (I;I) homozygotes respond better to Viagra than (D;I) or (D;D) individuals, in a study of 100+ Caucasian men with erectile dysfunction. (OR 3.07, CI: 1.03 - 9.13, p=0.04).


 * (I;I) homozygotes are are higher risk for early-onset psoriasis, with an odds ratio of 1.88 (CI: 1.12-3.15, p=0.016).

(I) is found more commonly in sherpas