Moyamoya Syndrome Risk Factors & Causes

Moyamoya syndrome is a rare progressive vascular disorder that involves the blocking or narrowing of the skull's carotid artery, which reduces blood flow to the brain. At the base of your brain, tiny blood vessels erupt to try to supply blood to the brain. The blood vessels aren't capable of providing necessary oxygen and blood to the brain, so the patient will suffer a brain injury, the severity of which will vary widely. There is no known root cause of Moyamoya syndrome, but certain characteristics increase the likelihood of developing the disease.

Associated Conditions

Some studies have linked Moyamoya disease with other conditions, including hyperthyroidism, neurofibromatosis type 1, sickle cell anemia, and Down syndrome. Individuals with these conditions may have a higher chance of developing comorbid Moyamoya syndrome.

Unfortunately, there has not been a great deal of research establishing why the comorbidity rates exist, and scientists have different theories. It's possible these disorders are all affected by the same gene or group of genes. It's also possible certain aspects of the associated disorders can increase the chances of narrowing blood vessels in the brain. Until more conclusive research is done regarding comorbidity rates, we don't have an explanation for why these diseases often occur concurrently. We just know they do.

Genetic Link

Research into the genetics of Moyamoya disease has been limited, but based on information about who the disease affects and how it does so, there is strong evidence indicating a genetic link. If a person's family member developed Moyamoya disease, they have a risk factor between thirty and forty times higher than the general population. This risk factor was calculated based on statistics regarding the individuals with Moyamoya syndrome. Thirty to forty times more patients had a relative with this condition than those who had no family history of the disease.

Some research indicates changes to the RNF213 gene might be related to Moyamoya syndrome. Other unidentified genes may also play a part in the development of this condition. The purpose of the RNF213 gene is to provide instructions for the construction of a protein with an unknown use. Studies suggest RNF213's protein is a component of blood vessel development. When this gene creates an incorrect protein, it's possible this causes the gradual blocking of blood vessels in the brain.