Moyamoya disease (MMD) shows progressive cerebral angiopathy characterized by 
bilateral internal carotid artery stenosis and abnormal collateral vessels. 
Although ∼ 15% of MMD cases are familial, the MMD gene(s) remain unknown. A 
genome-wide association study of 785,720 single-nucleotide polymorphisms (SNPs) 
was performed, comparing 72 Japanese MMD patients with 45 Japanese controls and 
resulting in a strong association of chromosome 17q25-ter with MMD risk. This 
result was further confirmed by a locus-specific association study using 335 
SNPs in the 17q25-ter region. A single haplotype consisting of seven SNPs at the 
RNF213 locus was tightly associated with MMD (P = 5.3 × 10(-10)). RNF213 encodes 
a really interesting new gene finger protein with an AAA ATPase domain and is 
abundantly expressed in spleen and leukocytes. An RNA in situ hybridization 
analysis of mouse tissues indicated that mature lymphocytes express higher 
levels of Rnf213 mRNA than their immature counterparts. Mutational analysis of 
RNF213 revealed a founder mutation, p.R4859K, in 95% of MMD families, 73% of 
non-familial MMD cases and 1.4% of controls; this mutation greatly increases the 
risk of MMD (P = 1.2 × 10(-43), odds ratio = 190.8, 95% confidence interval = 
71.7-507.9). Three additional missense mutations were identified in the 
p.R4859K-negative patients. These results indicate that RNF213 is the first 
identified susceptibility gene for MMD.