represents a fairly common variant in the CASP7
gene on chromosome 10, consisting of a deletion of two bases (TT). Roughly 25% of any population carry at least one rs10553596
(-) alleles, with somewhat higher frequencies in African populations.
An intriguing - though preliminary - report indicates that ApoE4 homozygotes, who are at relatively high risk for late-onset Alzheimer's disease, have their risk reduced (by about half) if they carry at least one rs10553596 minor allele, although it is also possible that the variant delays the age of onset (rather than protects against the disease). The protective effect was not observed for ApoE4 heterozygotes.[PMID 27358062]