A Close Look at the Genome and the Unbalanced Stratification of the Qatari Population

Abstract

Microsatellites are segments of the DNA comprised of repeated sequences of 4 to 8-base pair units that are found throughout the genome of eukaryotes. Most microsatellites are located at non-coding regions of the genome and consequently mutations in the microsatellite regions are often not causatives of disease. This allows these regions to be highly polymorphic in a population and gives a signature DNA marker for each individual. At the same time, it is often expected to see a wide genetic diversity of alleles present in the populations. In humans, microsatellites, or short tandem repeats (STRs) are standard genetic markers used for human identification in forensic cases and parentage determination.Databases of allele frequencies from various ethnic groups have been established in various parts of the world. In Qatar, as close-kin marriages are customary, homozygosity and possible reduced genetic variability have been a concern. A previous study, however, has concluded that the standard forensic markers are a valid tool for human identification because no substantive reduction of genetic variation has been observed as a result of consanguinity in the Qatari community.In a more recent study, it has been determined that the Qatari population is subdivided into three main ethnic groups, of Bedouin, African or Persian ancestry. This segregation has been genetically significant through studies in single nucleotide polymorphism, or SNP studies. Since SNPs and microsatellite DNA are inherited in a similar fashion, it is expected that there are different allele frequencies for assessed microsatellite loci for each of the populations. Moreover, the allelic heterogeneity in a population is closely linked to interbreeding. Since the Qatari Bedouin population has been closely associated with the practice of consanguinity as evidenced through SNP studies, it is therefore also expected to see higher homozygosity in the Bedouin subpopulation as compared to the other two subpopulations.In recent years diabetes occurrences in the Qatari populations have reached an epidemic level. Like many other diseases where both lifestyle as well as genetics may play a role in the onset of this disease, the microsatellite loci may serve as markers genetically linked to some of the non-communicable disease such as diabetes.The main aim of this study is to understand the genetic variability across the subpopulations of the Qatari nationals. The result can be used to develop new forms of personalized health care that is specific to members of the stratified Qatari subpopulations. The information allows for more efficient treatments and better management to the growing Qatari populations. To accomplish these goals, blood samples are collected from 300 individuals, with 100 from each subpopulation. AmpFISTR® Identifiler® Plus PCR Amplification Kit is used for a multiplex analysis of 15 tetranucleotide loci. The resulting data are analyzed to produce allele frequencies of each of the loci for the corresponding subpopulations. The gene diversity within and among the subpopulations are analyzed and the detection of consanguinity through the application of Hardy-Weinberg is discussed. The sub-profiles for each of the three Qatari subpopulations – Bedouin, African and Persian – are presented. Finally, the concept of personalized health care with respect to diabetes is introduced and the clinical applications relevant to the populations are discussed.