The most abundant form of genetic variation in any genome is known as the single nucleotide polymorphism (SNP). A SNP is the substitution of a single nucleotide in a stretch of DNA. When this single nucleotide change reaches high frequency in a population it is referred to as SNP, however when this change results in the loss of function of a specific gene we refer to this as a mutation. With reference to canine genetic testing, a large proportion of disease causing mutations are the result of single nucleotide changes inherited in an autosomal recessive manner. These mutations can be assessed using small amounts of DNA extracted from a buccal swab collection.