An association betwene the apolipoprotein E 4 (APOE 4) allele and pathological changes in Alzheimer's disease (AD) is now well established. We analyzed the APOE genotype in patients with another amyloid forming disease, Down's syndrome (DS). It is well-known that patients with DS develop the neuropathological features of AD if they reach middle adult life. The amyloid precursor protein gene is located on chromosome 21 and increased expression of this gene over a patient's lifetime is thought to underlie the development of this pathology.
We examined the APOE genotypes of 19 cytogenetically confirmed DS patients. The allele frequencies in this group did not differ from the general population. Our data suggest that the APOE 4 is not essential pathomechanism of AD pathology in patients with DS. P{rospective analysis of the occurrence of AD in DS population and APOE genotype is warranted.