FBXL4 and Progressive microcephaly: Homozygous or compound heterozygous variants were detected in six recently described or well established disease genes: SLC13A5 (epileptic encephalopathy, MIM 615905); FBXL4 (mitochondrial DNA depletion syndrome 13, MIM 615471); ZNF335 (microcephaly in a single family, MIM 615095); SLC1A4 (spastic tetraplegia, thin corpus callosum, and progressive microcephaly, MIM 616657); TRAPPC11 (limb girdle muscular dystrophy type 2S, MIM 615356); and ABCA4 (cone-rod dystrophy, MIM 604116).