ASSOCIATION OF THE HLA-A2 ALLELE WITH AN EARLIER AGE-OF-ONSET OF ALZHEIMERS-DISEASE

Introduction - The HLA-A2 allele has recently been considered as a ris k factor in AD by advancing the age at onset of the disease, especiall y in subjects who were homozygous for the apoE epsilon 4 allele. Mater ial and methods - We examined the distribution of apoE genotypes and A 2 allele as a function of age at onset in 109 patients with sporadic a nd familial AD. Results - In the early onset (less than or equal to 60 years) and late onset (>75 years) AD groups, there was, respectively, a 2.2 year and a 2.7 year earlier onset in the A2 positive cases. Age effect was not apparent in the middle onset (61-75 years) AD group. T he effect of A2 allele on the age at onset was not different between f amilial and sporadic AD cases. The presence or absence of the A2 allel e did not modify mean age at onset in the groups homozygous and hetero zygous for epsilon 4, and in cases with no epsilon 4 alleles. Conclusi on - Though the sample size was small, there is a trend in favor of an A2 effect on age at onset. Additionally, there is no evidence of inte raction between A2 and apoE epsilon 4 alleles on age at onset of AD.