Heterozygous de novo variants inCSNK1G1are associated with syndromic developmental delay and autism spectrum disorder

The gamma-1 isoform of casein kinase 1, the protein encoded byCSNK1G1, is involved in the growth and morphogenesis of cells. This protein is expressed ubiquitously among many tissue types, including the brain, where it regulates the phosphorylation of N-methyl-D-aspartate receptors and plays a role in synaptic transmission. One prior individual with a de novo variant inCSNK1Gpresenting with severe developmental delay and early-onset epilepsy has been reported. Here we report an updated clinical history of this previously published case, as well as four additional individuals with de novo variants inCSNK1G1identified via microarray-based comparative genomic hybridization, exome, or genome sequencing. All individuals (n = 5) had developmental delay. At least three individuals had diagnoses of autism spectrum disorder. All participants were noted to have dysmorphic facial features, although the reported findings varied widely and therefore may not clearly be recognizable. None of the participants had additional major malformations. Taken together, our data suggest thatCSNK1G1may be a cause of syndromic developmental delay and possibly autism spectrum disorder.