Fig. 1.

Clinical categories in the cohort and summary of WES findings. a Based on the brain structural findings and accompanying features, this cohort is grouped into nonsyndromic brain malformations (38 %), syndromic brain malformations (23 %), nonsyndromic DD/ID (16 %), and syndromic DD/ID (23 %). b Based on the brain structural defects, families can be further grouped into corpus callosum abnormalities, cortical dysgenesis, microcephaly, hindbrain malformations, and white matter changes; families may be counted in more than one of these groups. c Summary of WES findings (including CNVs): We identified a known variant in a known gene in 2 families (6 %), 10 novel variants in known genes in 9 families presenting reported clinical features (29 %), 7 novel variants in 6 known genes with phenotypic expansion in 6 families (19 %), and 12 novel disease candidates in 11 families (36 %). d The disease genes/candidates identified in this study can be grouped into several biological processes, including mitochondrial enzymes (metabolic or tRNA synthetase), lysosomal enzymes, motor proteins, trafficking proteins, DNA replication, DNA repair, transcription, mRNA splicing, synaptic transmission, signaling pathways, apoptosis, and transmembrane proteins