Polymorphism of Apo lipoprotein E gene and the risk of multiple sclerosis

Abstract

Background: Apolipoprotein E (ApoE) gene encodes an important protein in reforming injuries of central nervous system (CNS). It is assumed that various ApoE alleles may be functionally different. The purpose of this study was to investigate the distribution of ApoE genotypes in multiple sclerosis (MS) patients in a small cohort of Iranians.

Methods: In this case-control study, blood samples of patients and healthy volunteers were collected (n = 40) from Neurology Clinic of Alzahra Medical Complex. The ApoE genotypes were determined using DNA extracted from the samples by polymerase chain reaction (PCR) techniques followed by digestion with HhaI restriction enzyme. The results were adjusted for age of MS onset, sex, expanded disability status scale (EDSS), and type of MS (primary or secondary progressive). Results were statistically analyzed using chi-square test.

Results: The ApoE3/E3 genotype was detected in the majority of MS patients and the control group. Frequency distribution of E4 allele did not differ significantly between the two groups. There was no difference between ApoE allele and age of disease onset, sex, expanded disability status, or type of multiple sclerosis.

Conclusions: We found no significant differences in genotype frequency between patients with multiple sclerosis and the control group. Despite the fact that small sample size was a limitation for our study, it seems that ApoE polymorphism may not be useful as a marker for screening patients with multiple sclerosis.

Keywords: Allele; Apolipoprotein E; Gene; Multiple Sclerosis; Polymorphism.

Figure 1

Digestion of PCR amplified ApoE gene with HhaI restriction enzyme Lanes 1 and 4 show heterozygote E3/E4 genotype (91, 72, 48, and 53 bp bands). Lanes 2 and 3 show homozygote E3/E3 genotype (91, 48, and 53 bp bands).

Figure 2

The frequency of E3/E4 genotype of the patients in different types of MS (RR and SP)