The neuropsychological profile of an individual with early-onset CSF1R- related disorder with biallelic mutation

CSF1R-related disorder (CSF1R-RD) is a rare, rapidly progressive microgliopathy due to Colony Stimulating Factor 1 Receptor (CSF1R) gene mutation, resulting in movement disorder and dementia in young people. Clinical phenotypes are bimodal, including middle-age onset with a monoallelic mutation and early childhood onset with a biallelic mutation. The latter, more proliferative phenotype, has historically been known as Brain Abnormalities, Neurodegeneration, and Dysosteosclerosis (BANDDOS). There are no research studies characterizing cognition in biallelic CSF1R-RD. We present the neuropsychological profile of a 21-year-old woman with biallelic disease. This patient completed the Montreal Cognitive Assessment (MoCA), Dementia Rating Scale-2 (DRS-2), Wechsler Adult Intelligence Scale-IV selected subtests, Trail Making Test, Boston Naming Test-15, and mood measures. Performance was normal on the MoCA (28/30) but below average on the DRS-2 (123/144). The full neuropsychological profile revealed impaired general and verbal processing speed but preserved naming and memory retention. Findings represent the first formal cognitive characterization of biallelic CSF1R-RD, confirming a profile consistent with monoallelic CSF1R-RD. In CSF1R-RD, comprehensive neuropsychological evaluation is needed, as brief cognitive screening alone may fail to fully characterize the cognitive impact of the disease.