It is notable that no example of a Haplogroup IJ* Y-chromosome has been found among any modern human population; the existence of the Haplogroup IJ node has been inferred from the fact that certain mutations are shared in common among all Y-chromosomes belonging to the descendant haplogroups I and J. The lack of any examples of Haplogroup IJ* belonging to neither Haplogroup I nor Haplogroup J complicates any attempt to deduce the geographical location where Haplogroup IJ first appeared; however, the fact that both Haplogroup I and Haplogroup J are found among modern populations of the Caucasus, Anatolia, and Southwest Asia tends to support the hypothesis that Haplogroup IJ derived from Haplogroup F in the vicinity of West Asia or the Middle East and subsequently spread throughout Western Eurasia.
^Haplogroup LT (L298/P326) is also known as Haplogroup K1.
^Between 2002 and 2008, Haplogroup T-M184 was known as "Haplogroup K2". That name has since been re-assigned to K-M526, the sibling of Haplogroup LT.
^Haplogroup K2a (M2308) and its primary subclade K-M2313 were separated from Haplogroup NO (F549) in 2016. (This followed the publication of: (2016) "Punctuated bursts in human male demography inferred from 1,244 worldwide Y-chromosome sequences". Nature Genetics '48' (6): 593–9. DOI:10.1038/ng.3559. PMID 27111036. In the past, other haplogroups, including NO (M214) and K2e had also been identified with the name "K2a".
^ Haplogroup K2b (M1221/P331/PF5911) is also known as Haplogroup MPS.
^ Haplogroup K2e (K-M147) was previously known as "Haplogroup X" and "K2a" (but is a sibling subclade of the present K2a).