Haplogroup G2a1 and its subgroups represent the majority of haplogroup G samples in some parts of the
Caucasus Mountains area. They are found only in tiny numbers elsewhere. So far all G2a1 persons have a value of 10 at
STR marker DYS392. G2a1a persons also typically have higher values for DYS385b, such as 16, 17 or 18, than seen in most G persons.
The North Ossetians in the mid northern Caucasus area of
Russia belong overwhelmingly to the G2a1 subgroup based on available samples. The South Ossetians and
Svans generally south of North Ossetia have significant number of G2a1 persons, but population percentages have not yet been provided.
The presence of the SNP P18 mutation characterizes G2a1a's only subgroup, G2a1a. The reliability of both P16 and P18 in identifying everyone in each of these categories has been questioned and individual components of the SNP have to be examined.
Ashkenazi Jewish G2a1a men with northeastern European ancestry form a distinct cluster based on STR marker values. Men from the Caucasus and men from eastern Europe also form distinctive STR clusters.