Clinical and genetic spectrum of patients with IRF2BPL syndrome.

Interferon regulatory factor 2 binding protein-like (IRF2BPL) is a single-exon gene that is ubiquitously expressed in various tissues, including the brain. IRF2BPL encodes a transcription factor with two zinc-finger domains that potentially downregulate WNT signaling in the nervous system. Pathogenic IRF2BPL variants have been reported to cause developmental delay, seizures, myoclonus epilepsies, autistic spectrum disorder, and other neurodevelopmental disorders. Exome sequencing of 10 patients with developmental delay and/or epilepsy from nine families revealed nine pathogenic IRF2BPL variants, of which eight were novel: five missense, one in-frame indel, and three truncating variants. Using reported pathogenic and benign variants, we highlight here several regions of IRF2BPL that deviate in the frequency of pathogenic and benign variants. This study of detailed clinical and genetic information shows that IRF2BPL missense and in-frame indel variants are often associated with seizures and developmental delay.