Further inspection (because HPO annotations were incomplete) found three additional, adult-onset haploinsufficiency disorders encoding by genes showing a 50–80% reduction in the maturing mouse synapse proteome (Figure 6—figure supplement 2): Vcp (Frontotemporal Dementia) (fold change, FC = 0.48; p=0.002); Atl1 (hereditary spastic paraplegia) (FC = 0.19, p=0.00004); Dmxl2, (Polyendocrine-polyneuropathy syndrome) (fold change: 0.28, p=0.00004). Here, DMXL2 is linked to hereditary spastic paraplegia.