UBE2D1 and frontotemporal dementia: Notably, proteins linked to the ubiquitin–proteasome system, such as UBE2D1 | UBB (β = 0.61, P = 9.7 × 10−26), UBE2D3 | UBB (β = 0.49; P = 1.8 × 10−23) and PSMB3 (β = 0.26, P = 3.3 × 10−4), were also identified, further supporting the established role of impaired protein degradation in FTD pathogenesis21.