Haplogroup pre-JT is a human mitochondrial DNA haplogroup (mtDNA). It is also called R2'JT.

Haplogroup pre-JT is a descendant of the haplogroup R. It is characterised by the mutation T4216C. The pre-JT clade has two direct descendant lineages, haplogroup JT and haplogroup R2.^{[citation needed]}

According to YFull MTree, haplogroup R2'JT has allegedly been sequenced in at least three individuals, among whom one came from ancient Egypt^[1] and one from modern Denmark.^[2] However, Ian Logan mutationally interpreted the Denmark sample as being a member of T1a.^[3]

Its major subclade is Haplogroup JT, which further divides into Haplogroup J and Haplogroup T. Its other subclade is Haplogroup R2, which has such branches as R2a, R2b, and R2c.

• Genealogical DNA test
• Genetic genealogy
• Human mitochondrial genetics
• Population genetics