Genetic factors have been suggested to contribute to the etiology of moyamoya 
disease. The authors have previously reported an association between moyamoya 
disease and several alleles for human leukocyte antigens (HLA). To further 
specify the genetic component of moyamoya disease, a linkage study of moyamoya 
disease using markers on chromosome 6, where the HLA gene is located, was 
performed. The 15 microsatellite markers of chromosome 6 were studied in 20 
affected sibling pairs. From an identical-by-descent analysis of these markers, 
an allele with possible linkage to moyamoya disease was identified. Sharing of 
the allele among affected members in 19 families was investigated, considering 
the haplotype. The marker, D6S441, might be linked to moyamoya disease. 
Considering the haplotype, the allele was shared among the affected members in 
16 (82%) of the 19 families, but not in two others. In one family, sharing of 
the allele could not be determined because of low heterozygosity. Further 
studies are necessary to clarify multiple genetic factors that are definitely 
linked with moyamoya disease.