The APOE gene is located on chromosome 19 and encodes for the apolipoprotein E (ApoE), a plasma glycoprotein involved in the transport of cholesterol which binds to amyloid protein. ApoE performs the function of lipid carrier; primarily synthesized in the liver, it constitutes the 1-2% of high density lipoprotein (HDL) and plays a critical role in the formation of VLDL (very low density lipoprotein) of chylomicrons . In particular, it mediates the binding, internalization and catabolism of lipoproteins. The APOE gene, located in 19q13.2, encodes a protein of 299 amino acids actively synthesized at the level of hepatocytes. The gene is polymorphic with three common alleles * e2, * e3 and e4 * that produce three protein isoforms E2, E3 and E4. These isoforms differ in amino acid sequence at positions 112 and 158. Alzheimer’s disease is a degenerative disease of the brain cells that causes dementia, which is a progressive decline of intellectual functions and memory, changes in personality and behavior.

It occurs mainly after age 60, although there are much rarer cases of onset between 30 and 50 years. There are sporadic (75%) and familial forms (25%). The APOE4 allele has been associated with Alzheimer’s disease with late-onset familial and sporadic forms. As early as 1989 it was described the association of this gene with the disease: the ApoE e4 allele was more frequent in patients suffering from the disease compared to controls. The disease risk is dose-dependent (presence of only one allele or alleles of two E4) as well as the lowering of the age of onset. The presence in the heterozygous allele e4 would increase the risk factor of developing the disease (approximately 3 times higher compared to its absence); the presence in homozygosity would result in an even greater risk. Subsequent studies have also explained the reasons for this association: the ApoE e4 binds with higher affinity amyloidogenic fibrils causing more precipitation and therefore a faster formation of senile plaques. The e2 allele is more associated to family hyperlipoproteinemia type III, characterized by xanthomas, and high levels of triglycerides and cholesterol.

Real Gene proposes the panel for genotyping two ApoE polymorphisms constituted by ApoE C112R (C130R) and ApoE R158C (R176C), both available in combinations of 24, 48 and 72 reactions. The panel is supplied with the application Genosoftware for ApoE, developed by the company to automatically determine the genotype of the test subject. This is done by simply inserting the data provided by the software tool for real-time PCR for the two polymorphisms at the end of the instrumental race. The software is only available for the Windows platform and is supplied on a CD-ROM (includes a tutorial for use in Adobe PDF format)

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