Gene Polymorphisms as Markers of Disease Susceptibility

The most widespread diseases of modern man have a polygenic basis, including genetic predisposition and factors in the external environment. Such is the case with cardiovascular disease, malignancy, diabetes and so on. It should be borne in mind that risk factors usually include disorders that are themselves multifactorial, which further indicates the complexity of pathophysiological mechanisms. In the investigation of genetic factors in polygenic diseases studies are underway to determine the association with specific gene polymorphisms. Genetic or DNA polymorphisms are differences in the hereditary basis which are normally found in human populations. The human genome consists of 3×109 nucleotide (base) pairs, and it is considered that, on average, every 1000th nucleotide is polymorphic, i.e. varies between two loci or two individuals. The most common type of gene polymorphisms is the single nucleotide polymorphism (SNP). Although gene polymorphisms are an expression of normal variations in the hereditary basis, their effect on the phenotype is interesting, especially the association with proneness to certain diseases. Association studies examine the incidence of certain genetic variants, i.e. genetic polymorphisms in a group of patients, and compare it with the data of a healthy population. The results are often contradictory, so the number of polymorphisms whose role as markers of genetic predisposition has been clearly confirmed is still small. In this paper we review literature data and present experiences from our laboratory in studying genetic polymorphisms as susceptibility factors for the occurrence of thrombophilia and atherosclerosis and its clinical manifestations. Najrasprostranjenije bolesti savremenog čoveka imaju poligensku tj. multifaktorsku osnovu, koja uključuje genetičke faktore predispozicije i činioce iz spoljne sredine. Takav je slučaj sa kardiovaskularnim bolestima, malignitetom, dijabetesom itd. Treba imati na umu da faktori rizika obično obuhvataju poremećaje koji su sami po sebi takođe multifaktorski, što dodatno ukazuje na kompleksnost patofizioloških mehanizama. U okviru istraživanja genetičkih činilaca kod poligenskih bolesti pristupa se studijama asocijacije sa određenim genskim polimorfizmima. Pod genskim, odnosno DNK polimorfizmom podrazumevaju se razlike u naslednoj osnovi koje se normalno sreću u humanim populacijama. Genom čoveka se sastoji od 3×109 nukleotidnih (baznih) parova a smatra se da je u proseku svaki 1000. nuk