Dear Editor

In 2009, Guo et al. [1] first reported that mutation carriers of the vascular smooth muscle cell-specific isoform of α-actin (ACTA2) gene can have a diversity of vascular diseases, including thoracic aortic aneurysms and dissections, coronary artery disease, premature ischemic stroke, and moyamoya disease (MMD). These results indicate that heterozygous ACTA2 mutations can increase the risk for MMD and ACTA2 may be a genetic susceptibility gene to MMD. However, subsequent studies in two ethnic populations demonstrated that ACTA2 was not a major disease-causing gene for MMD. One study did not detect the ACTA2 mutation in 53 Japanese MMD patients [2]. Another study found only one missense mutation of ACTA2 in one of the 39 European patients with MMD [3]. These conflicting results suggest that it is premature to conclude an association between ACTA2 and MMD.

MMD is an uncommon cerebrovascular disease characterized by progressive occlusion of terminal portions of the internal carotid arteries causing cerebral ischemia and haemorrhage. The previously reported cases were mainly from Asian populations, especially in Japan. To date, the etiology of MMD remains unclear. In order to clarify the currently uncertain association of ACTA2 with MMD, we conducted a replication study in a Chinese Han population.

Fifty-five patients with MMD (male/female = 24/31, mean age 33·4 ± 12·1 years) were recruited to our study. All nine exons and exon-intron boundaries of ACTA2 were sequenced directly. However, genomic sequencing did not find any ACTA2 mutation. Our findings further confirmed that ACTA2 did not play an important role in the pathogenesis of MMD. Owing to some limitations of the sample size, however, larger studies are warranted to further evaluate the possible association of ACTA2 or other genes and MMD in varied populations.


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