A novel IRF2BPL truncating variant is associated with endolysosomal storage.

De novo mutations in the IRF2BPL gene have been identified to date in 18 patients presenting with neuromotor regression, epilepsy and variable neurological signs. Here, we report a female child carrying a novel heterozygous truncating variant in IRF2BPL. Following normal development for two and half years, she developed a progressive neurological condition with psychomotor regression, dystonic tetraparesis with hyperkinetic movements, but no overt epilepsy. Skin biopsy revealed enlarged lysosomes containing granular and tubular material, suggestive of a lysosomal storage disorder. This case expands the IRF2BPL phenotypic spectrum, for the first time providing evidence of endolysosomal storage.