WDR41 and Smith-Magenis syndrome: Another study suggested that C9orf72 forms a complex with two other proteins, Smith-Magenis Syndrome Chromosome Region, Candidate 8 (SMCR8) and WD repeat domain 41 (WDR41), and this complex acted as a GEF for Rab GTPases such as Rab39b, Rab8a and Rab1a, thereby facilitating their role in endocytic trafficking in autophagy (Sullivan et al., 2016).