In molecular evolution, a haplogroup (from the Greek: απλούς,
haploûs, "onefold, single, simple") is a group of similar
haplotypes that share a common ancestor having the same single
nucleotide polymorphism (SNP ) mutation in both haplotypes.
Because a haplogroup consists of similar haplotypes, this is
what makes it possible to predict a haplogroup from haplotypes.
A SNP test confirms a haplogroup. Haplogroups are assigned
letters of the alphabet, and refinements consist of additional
number and letter combinations, for example R1b1. Y-chromosome
and mitochondrial DNA haplogroups have different haplogroup
designations. Haplogroups pertain to deep ancestral origins
dating back thousands of years. In human genetics, the
haplogroups most commonly studied are Y-chromosome (Y-DNA)
haplogroups and mitochondrial DNA (mtDNA ) haplogroups, both of
which can be used to define genetic populations. Y-DNA is passed
solely along the patrilineal line, from father to son, while
mtDNA is passed down the matrilineal line, from