434 Pumilio2 haploinsufficiency causes a neurodevelopmental disorder with ataxia

Objectives/Goals: Our goal is to determine whether insufficient Pumilio2 (Pum2) leads to neurological disorders. We identified predominantly young patients with mutations in PUM2 who suffer from developmental delays, motor incoordination, seizures, and so on. We will utilize Pum2 null mice to identify behavioral issues and neural degeneration. Methods/Study Population: We conducted several neurobehavioral assays with the Pum2 mutant mice (an estimated 40 mice) throughout their development. These assays measure learning and memory, motor coordination, spatial recognition, hyperactivity, and social cues. In addition to these experiments, we conducted immunofluorescence and Nissl staining to characterize brain morphology and Purkinje cells. Additionally, we collected patient-derived fibroblasts for qPCR and Western blot to measure the mRNA and protein levels of PUM2 in the different variants. Using both eCLIP and RNA sequencing, we will determine and rank targets bound by Pum2 in the murine brain. Results/Anticipated Results: At 12 weeks, we discovered Pum2 mutant mice exhibit neurological phenotypes that worsen with age development, such as motor incoordination, muscle atrophy, hyperactivity, impulsiveness, and compulsiveness. We observed a decrease in dendritic density in the Purkinje cells at 10 weeks of age, but no neural degeneration. However, we observed a reduction in dendritic density and aggressive Purkinje cell degeneration much later in adulthood. We obtained patient-derived fibroblasts to conduct Western and qPCR. We found that the missense mutations lead to a decrease in PUM2 protein and mRNA levels. These findings exhibit phenotypes similar to those observed in PUM2 patients, suggesting that insufficient levels of PUM2 lead to neurodevelopmental disorders and ataxia. Discussion/Significance of Impact: Pumilio2 is an RNA-binding protein from the PUF family that either promotes mRNA degradation or inhibits translation. It controls dendritic development and synaptic activity. PUM2 may be a novel ataxia gene that manifests neurodevelopmental problems.