{{Rsnum 
|rsid = 13447447
|Gene = ACE
|Orientation=plus
|geno1=(-;-)
|geno2=(-;N)
|geno3=(N;N)
|Chromosome=17
|position=58919623
|Status=Deleted
}}[[rs13447447]] 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]]
* [[rs4340]] 
* [[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). {{PMID|12837457}}

*(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).{{PMID|18031458}}

{{PharmGKB
|RSID=rs13447447
|Name_s=ACE:I/D
|Gene_s=ACE
|Feature=Intron
|Evidence=PubMed ID:12837457
|Annotation=This variant is one of the insertion/deletion variant in intron 16 of the ACE gene. It is associated with sildenafil response for erectile dysfunction patients. Patients with D allele have elevated ACE serum concentrations and are less likely to respond to sildenafil.
|Drugs=sildenafil
|Drug Classes=
|Diseases=Erectile Dysfunction
|Curation Level=Curated
|PharmGKB Accession ID=PA161822204
}}