All of the following human genetic haplogroup names are shared between Y-chromosome and mitochondrial DNA haplogroups EXCEPT:

The haplogroup U is not shared between the Y-chromosome and mitochondrial DNA haplogroups because it refers specifically to the mitochondrial haplogroup U, which is solely associated with maternal lineages. In contrast, the Y-chromosome haplogroups exclusively trace paternal lineages. Therefore, while other haplogroup names may be present in both mitochondrial and Y-chromosome haplogroups, haplogroup U is unique to maternal lineages and not found in the Y-chromosome haplogroups.