ApoE genotypes: Risk factor for Alzheimer's Disease

Alzheimer's disease (AD) is a neuro-degenerative disorder resulting in memory loss and other cognitive impairments. The most prevalent genetic risk factor for AD is ApoE genotype. There is evidence that presence of Apoε4 reduces the age of onset for AD. ApoE mediated mobilisation of cholesterol in the CNS is of particular importance for synapse plasticity and repair of neurons. Present PCR-RFLP based study is the first report on correlation of ApoE alleles with AD and lipid profile in 20 subjects (comprising of 14 patients and their first-degree relatives) of Indian origin. In AD patients and their relatives, nearly 71% subjects were positive for one Apoε4 allele, though only two patients were found to be homozygous for the Apoε4/4 genotype. Overall Apoε4 frequency in control subjects (n = 46) was 0.11 and 0.43 in AD patients and their relatives. The odds ratio between patients and control subjects for Apoε4 allele was 6.15 with X ² = 12.612. The association between the Apoε4 allele and late-onset AD was highly significant (p < 0.0001). The serum cholesterol was marginally higher in individuals with Apoε4 genotype. Serum LDL levels of Apoε4 genotype were significantly higher in the test group (p < 0.05) comprising of AD patients and their first degree rellatives. Elucidation of the structure and function of different cellular cholesterol pools is necessary for understanding the coherence between cholesterol and AD.