Alpha-1,6-mannosyltransferase involved in glycosylphosphatidylinositol-anchor biosynthesis. Transfers the second mannose to the glycosylphosphatidylinositol during GPI precursor assembly. Glycolipid biosynthesis; glycosylphosphatidylinositol-anchor biosynthesis. Not N-glycosylated. The disease is caused by variants affecting the gene represented in this entry. Belongs to the PIGV family.