Date of Award

2010

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Environmental Science

First Advisor

D r. Basam Ali

Second Advisor

Dr. Fatmc Al Anouti

Third Advisor

Dr. Yousef Abdulrazzaq

Comments

Introduction; Familial hypercholesterolemia is a serious health problem in most populations including Arabs leading to increased morbidity and mortality. This illness is hereditary in an autosomal dominant manner affecting 1 in 500 people and is mainly caused by mutations in LDLR and Apolipoprotein B genes. The manifestations of this disease are preventable by medical intervention and changes to life style. However, prevention is only possible if detection of the disease is made early in life. Moreover, the WHO strongly recommends that governments establish programs for identifying and registering familial hypercholesterolemia patients and their families. There are no molecular data available on this illness in the UAE despite clinical and biochemical studies indicating high prevalence of hypercholesterolemia in UAE Arab populations. Objectives; this project aimed to identify the molecular basis of familial hypercholesterolemia in UAE Arab populations. Materials and methods; Blood samples were collected from suspected patients with high levels of cholesterol (>5mmol/L) followed by genomic DNA isolation and PCR amplification of all LDLR gene exons and splice sites and exons 26 and 29 of the Apo B100 gene. PCR products were first analyzed and visualized by agarose gel electrophoresis and then cleaned using a mixture of Exonuclease and Shrimp Alkaline Phosphatase enzymes (EXO-SAP) followed by direct DNA sequencing. The sequences obtained were compared to the published sequences for the two genes using the CLUSTALW alignment programme. In addition, we generated by site-directed mutagenesis some of the published missense mutations responsible for familial hypercholesterolemia in other populations and studied their subcellular localization by confocal microscopy. Results and discussion; Sequencing of the coding regions and splice sites of all LDLR exons and exons 26 and 29 from Apo B10 genes from over 40 hypercholesterolemic UAE individuals failed to reveal any clear pathogenic mutations. However, our analysis revealed 11 different polymorphisms reported with known ethnic backgrounds and we were able to calculate the allele and genotypes frequencies of those polymorphisms in UAE population. The failure to detect any pathogenic mutation in a representative group of hypercholesterolemic individuals from the UAE might indicate that this condition is caused by other factors including possibly other genetic and/or environmental factors. In support of this notion is the lack of any reports on cases of homozygous familial hypercholesterolemia in UAE population. This would be expected in the light of the very high rates consanguineous marriages (>50%) within most families of the UAE population. The confocal microscopy data confirmed that some of the studied mutations resulted in trafficking defects of the LDLR protein.

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