Allele ε4 of apolipoprotein E gene is less frequent in Down syndrome patient of the Sicilian population and has no influence on the grade of mental retardation

We evaluated the allele (and genotype frequencies in 60 Down syndrome (DS), 25 mothers and 57 controls from Sicily and its relation with mental retardation. DS patients and sex ratio (M:F) was 22.1 ± 10.5 and 1.14, respectively. Allele ε4 and ε3 frequencies were respectively lower (P = 0.015) and higher (P = 0.005) in DS patients compared to controls. Genotype ε3/ε4 and ε3/ε3 were less (P = 0.03) and more frequent (P = 0.001) in DS patients, with respective odd ratios of 0.31 (CI at 95%: 0.18-0.49) and of 4.4 (CI at 95%: 3.4-5.7). No difference of allele (distribution was found in function of the grades of mental retardation according to DMS-IV. Our results show that the implication of Apo-E4 in the pathogenesis of Alzheimer disease cannot be extrapolated in that of dementia of DS. © 2001 Elsevier Science Ireland Ltd.