Rare disease affecting the cerebellum and the bone marrow. Onset and symptoms vary among affected individuals. Atrophy and changes to the cerebellum cause problems including ataxia, dysmetria, clonus, nystagmus and these neurological issues worsen over time. Pancytopenia can result in extreme fatigue, anemia, neutropenia and thrombocytopenia. This disease is also associated with increased risk of blood malignancy particularly myelodysplastic syndrome and acute myeloid leukemia. Caused by inherited gain of function mutations in the SAMD9L gene. Inherited in an autosomal dominant pattern.