Haplogroup G-P303
| Haplogroup G-P303 (G2a3b1) | |
|---|---|
| Possible time of origin | perhaps 3,000-5,000 years BP |
| Possible place of origin | Perhaps Caucasus or Iran |
| Ancestor | Haplogroup G2a3b (L141) |
| Descendants | G2a3b1, G2a3b1a, G2a3b1b, G2a3b1c |
| Defining mutations | P303 or S135 (G2a3b1), L140 (G2a3b1a), U1 (G2a3b1a1), L13/S130 (G2a3b1a1a), L1266 (G2a3b1a1b), L497 (G2a3b1a2) Z725 (G2a3b1a2a), L42/S146 (G2a3b1a2a1a), Z1903 (G2a3b1a3), Z724 (G2a3b1a3a) |
In human genetics, Haplogroup G-P303 (P303) is a Y-chromosome haplogroup. It is a branch of haplogroup G (Y-DNA) (M201). In descending order, G-P303 is additionally a branch of G2 (P287), G2a (P15), G2a3 (L30 or S126) and finally G2a3b (L141). This haplogroup represents the majority of haplogroup G men in most areas of Europe west of Russia and the Black Sea. To the east, G2a3b1 is found among G persons across the Middle East, Iran, the southern Caucasus area, China and India. P303 exhibits its highest diversity in the Levant.
All G-P303 men carry the P303 or S135 SNP Y-DNA mutation. There are also some short tandem repeat (STR) findings among G-P303 men which help in subgrouping them. Many of the men have an unusual value of 13 for marker DYS388, and some have 9 at DYS568. STR marker oddities are often different in each G-P303 subgroup, and characteristic marker values can vary by subgroup. Often the values of STR markers DYS391, DYS392 and DYS393, however, are respectively 10, 11 and 14 or some slight variation on these for all G-P303 men.
P303 first became available for public testing in fall 2008, and the P designation indicates it was identified at the University of Arizona. The mutation is found on the Y chromosome at position 20104736. The forward primer is TTCTTATTTGCTTTGAAACTCAG. The reverse primer is ATTGGCTTATCAGATTGACG. The mutation involves replacement of T by C. This mutation was actually first identified as S135 at Ethnoancestry in London, England, but it took some time to realize that P303, which was independently identified, and S135 were the same.
Research studies have not yet dated the origin of G-P303. Based on the number of mutations seen in 67-marker STR values, the P303 mutation occurred about 3,000-4,000 years ago, and the major subgroups developed their mutations later. The spread to Europe in some subgroups seems to have occurred primarily in the period of 2,000 to 1,000 years ago based on comparisons of samples from Europe west of the Black Sea to samples from more easterly locales. Several subgroups may have originated within Europe.
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