Approximately one-third of children with autism spectrum disorder (ASD) reportedly lose skills within the first 3 years, yet a causal mechanism remains elusive. Considering evidence of strong genetic effects for ASD and findings that distinct phenotypes in ASD associate with specific genetic events, we examined rates of parent-reported regression in the Simons Simplex Collection with likely gene disrupting mutations from five distinct classes: FMRP target genes, genes encoding chromatin modifiers, genes expressed preferentially in embryos, genes encoding postsynaptic density proteins, and essential genes. Children with ASD and mutations in postsynaptic density genes were "more" likely to experience regression, while a trend suggested that children with ASD and mutations in embryonic genes were "less" likely to have skill losses.