Practice question

A single nucleotide polymorphism defines a variation at a single base position in the genome where two alternative nucleotides occur in a population at appreciable frequency, typically greater than one percent. These biallelic markers are the most abundant type of genetic variation, distributed across coding and non-coding regions, arising from point mutations, transitions or transversions. VNTR and STR involve variable numbers of tandem repeat units, while indels refer to insertions or deletions of one or more nucleotides, making SNP distinct as a single base substitution.