Haplogroup BT
| Haplogroup BT | |
|---|---|
| Possible time of origin | ~150,000-145,000 BP | 
| Possible place of origin | Africa | 
| Ancestor | A2-T | 
| Descendants | B-M60, CT | 
| Defining mutations | Page65.1/SRY1532.1/SRY10831.1, M42, M91, M94, M139, M299, P97, V21, V29, V31, V59, V64, V102, V187, V202, V216, V235 | 
Haplogroup BT M91, also known as Haplogroup A1b2 (and formerly as A4, BR and BCDEF), is a Y-chromosome haplogroup. BT is a subclade of haplogroup A1b (P108) and a sibling of the haplogroup A1b1 (L419/PF712).