Complex sentence: A single nucleotide polymorphism (SNP), a variation at a single site in DNA, is the most frequent variation in the genome, there are about 5-10 million SNPs in the human genome.
Split into simpler sentences: A single nucleotide polymorphism (SNP), a variation at a single site in DNA, is the most frequent type of variation in the genome. For example, there is an estimated 5-10 million SNPs in the human genome.