A Rare Genetic Cause of Young Onset Rapidly Progressive Dementia- First Report from India.

We present a case of a 40-year-old man with rapid decline in cognition followed by Parkinsonism, apraxia and stimulus sensitive myoclonus within 9 months of onset. Magnetic Resonance imaging (MRI) showed periventricular confluent white matter changes with persistent diffusion restriction even after 9 months. Clinical exome sequencing showed colony stimulating factor 1 receptor (CSF1R) gene mutation. The phenotype, MRI and genotype are suggestive of adult-onset leukoencephalopathy with axonal spheroids and pigmented glia (ALSP). This is the first case being reported from India. Differential diagnosis of young onset dementia is broad. Therefore, finding the exact etiology is challenging. Neuroimaging and genetic analysis greatly aid in the final diagnosis.