Every haplogroup name points to a specific mutation at a specific location on the Y chromosome. Here is exactly where J-FTE7366 sits across every reference genome. • T2T (CHM13v2.0): chrY:10,279,929, Yp11.2 • GRCh38/HG38: chrY:9,960,846 • GRCh37/HG19: chrY:9,798,455 J-FTE7366 sits on the short arm of the Y chromosome in the Yp11.2 region. It is fully accessible to all reference assemblies. Any Big Y test can reach it. Any Whole Genome Sequence can reach it. No special re-alignment is required. This stands in direct contrast to the two T2T-exclusive SNPs documented below it, J-Y637739 and J-Y637789, which sit on the long arm in the Yq11.223 ampliconic palindrome zone with no coordinate in either GRCh37 or GRCh38, and J-Y637804, sitting even further out in Yq12 at the distal tip of the long arm, also invisible to all prior assemblies. One lineage. Three regions of the Y chromosome. From the short arm to the very end of the long arm. Each one telling a different story about what current and past reference assemblies can and cannot see.
Thomas James Johnson III Vincek (2026) studied this question.