SNP or Single Nucleotide Polymorphism can simply be termed as copying error made by cells during the process of making new cells wherein a ‘wrong’ nucleotide is present in the DNA sequence in the place of a ‘correct’ nucleotide. For e.g., let’s assume that the normal sequence of a particular section of DNA in humans is AATGCT. A SNP is when the sequence becomes AATGCA, where the last letter (nucleotide) instead of ‘T’ is replaced with ‘A’. These copying errors are like typographical errors which lead to variations in the DNA. These typos in DNA might affect protein function and structure, when present within genes that form these proteins. These variations in the DNA are the root cause for  majority of health conditions, differences in response to drugs or diseases etc.

SNPs can be associated with lifestyle related conditions like diabetes, obesity and stroke. These SNPs also contribute to  difference in food metabolism e.g. lactose intolerance.