Naturally occurring splice variants dissect the functional domains of BHC80 and emphasize the need for RNA analysis

Abstract

Pathogenic PHF21A variation causes PHF21A‐related neurodevelopmental disorders (NDDs). Although amorphic alleles, including haploinsufficiency, have been established as a disease mechanism, increasing evidence suggests that missense variants as well as frameshift variants extending the BHC80 carboxyl terminus also cause disease. Expanding on these, we report a proposita with intellectual disability and overgrowth and a novel de novo heterozygous PHF21A splice variant (NM_001352027.3:c.[153+1G>C];[=]) causing skipping of exon 6, which encodes an in‐frame BHC80 deletion (p.(Asn30_Gln51del)). This deletion disrupts a predicted leucine zipper domain and implicates this domain in BHC80 function and as a target of variation causing PHF21A‐related NDDs. This extension of understanding emphasizes the application of RNA analysis in precision genomic medicine practice.