Chediak-Higashi Syndrome (CHS) is an exceedingly rare autosomal recessive disorder caused by mutations in the LYSTgene, classically characterized by oculocutaneous albinism, immunodeficiency, and progressive neurological decline. Fewer than 500 cases have been reported worldwide, and adult-onset presentations are exceptionally uncommon and often underrecognized.

Neurological examination showed severe sensorimotor polyneuropathy and cerebellar ataxia. Brain MRI demonstrated cortical and cerebellar atrophy. Peripheral blood smear revealed giant cytoplasmic granules in leukocytes, pathognomonic of CHS. Genetic testing confirmed a LYST gene mutation in both siblings. Despite supportive management, neurological symptoms progressed, while infection control improved with prophylactic measures.