POLYMORPHISM

It means the presence of many forms. It is the occurrence in a population of two or more alleles at a locus, in frequencies greater than that can be maintained by mutation. They are common in noncoding regions of DNA, and are merely alterations of DNA sequences. These genetic differences provide variation within a species. The ABO blood groups and human leukocyte antigens are examples of polymorphisms. Some polymorphisms are detected using DNA technology like polymerase chain reactions or direct DNA sequencing as for the detection of Restriction Fragment Length Polymorphisms (RFLP). Chromosome polymorphisms are detected using cytogenetic studies.