Case of Familial Moyamoya Disease Presenting 10 Years After Initial Negative Magnetic Resonance Screening in Childhood

BACKGROUND: Both genetic and environmental factors are considered to contribute to the onset of moyamoya disease, but the exact mechanism has not yet been clarified. Furthermore, the typical time course of progression to vessel occlusion has not been established, even in the genetically high-risk population. CASE DESCRIPTION: We present the case of a 21-year-old female with familial history of moyamoya disease. She underwent screening for moyamoya disease 10 years prior, but no abnormalities in magnetic resonance imaging or magnetic resonance angiography were found. She presented to our hospital for transient numbness of the left upper and lower extremities and dysarthria at the age of 21. She was diagnosed with moyamoya disease and underwent bilateral encephaloduroarteriosynangiosis. Gene analysis on the point mutation of RNF213, p.R4810K, was conducted for this patient, her younger sister with moyamoya disease, and their nonsymptomatic parents. A rare variant (p.R4810K) was positive in these sisters and their mother. CONCLUSION: We show a case of familial moyamoya disease diagnosed 10 years after the magnetic resonance imaging screening in childhood. We must carefully consider when, how, and for whom screening for moyamoya disease should be performed, taking into account familial history of the disease.