Genetics is now considered the most acknowledged field in studying human disease causes and considered a rich field in medical researches. Pharmacogenomics is a product of that researches and getting attention to personalize medicine to individuals through investing in the DNA based drug therapy [1,2]. Of all malignancies 1% is mainly caused by single-gene inheritance. Single gene, chromosomal, and multifactorial were used to describe hereditary conditions until the understanding of the interaction between different genes (polygenic inheritance) and including acquired somatic genetic disease category. About 5% of population after age of 25 years will have a disorder with a genetic basis .
Genetic Impact on Maxillofacial Surgery: Basic DNA Structure
DNA is a long polymer forming a chain of series of nucleotide molecules. Each nucleotide molecules has one molecule of deoxyribose sugar, one molecule of phosphoric acid and one nitrogenous base on the side of the sugar. There are four types of nucleotides in the DNA following the types of nitrogenous bases: Adenine (A), Thymine (T), Cytosine (C) and Guanine (G). The DNA helix model was first suggested by Watson and Crick in which the two polynucleotide chains run besides and opposite to each other. They are attached together by the nitrogen bases through hydrogen bonds with two types. The nitrogen base of the two attached stands of the DNA are paired in a constant arrangement in which Adenine always binds with Thymine and Cytosine always binds with Guanine. This will leads to stable hydrogen bonds between the pairs. The two DNA's stands are complementary twist around forming the double helix (Figure 1). A single turn of the helix is 3.4 nm in length with 10 base pairs and the helix diameter is 2 mm .