DDHD2 is mutated in SGP54, which is usually characterized by very early onset spastic paraplegia, intellectual disability, and white matter abnormalities (Schuurs-Hoeijmakers et al., 2012), but adult onset forms have been reported for both DDHD1 and DDHD2 (Doi et al., 2015; Dard et al., 2017). Here, DDHD2 is linked to Intellectual disability.