Apolipoproteína E e a doença de Alzheimer

Abstract

It is known that polymorphisms in the gene of the apolipoprotein E (apoE) are important risk factors in the development of the Alzheimer's disease (AD). The human gene apoE, which is mapped in the long arm of chromosome 19 (19q13.2), codes for a glycoprotein with 317 amino acids, which plays a basic role for the catabolism of triglyceride-rich components in the human body. In our species the apoE gene appears in the form of three main alleles, produced from two alterations in the DNA sequence, called epsilon2, epsilon3 and epsilon4. The identification of the variant epsilon4 of gene apoE as the most relevant genetic marker for the risk for late-onset AD suggests that cholesterol may have a direct involvement in the patho­genesis of this disease. However, apoE epsilon4 is not necessary nor enough to cause Alzheimer's disease. It only increases the risk of an individual to develop the illness, indicating that other environmental/genetic factors shoud play important roles in the development of the disease.