It can effect mRNA splicing and hence the expression of the protein which can lead to abnormality in concerned phenotype. Single nucleotide polymorphism ( SNP) is the simplest form of DNA variation among individuals. These simple changes can be of transition or transversion type and they throughout the genome at a frequency of one in 1,000 bp. They may be responsible for the diversity among individuals, genome evolution, the most common familial traits such as curly hair, interindividual diferences in drug response and complex and common diseases such as diabetes, obesity, hypertension and psychotic dis orders.