Michelle - I believe moyamoya is only hereditary in the Asian population.  However, if you read Dr. Scott's Q&A on the links page he says he has a former patient who's daughter also has moyamoya.  I think that is more the exception rather than the norm. - Shari

Hi Michelle-

I too asked Dr. Steinberg this question and he said it was highly unlikely.  I also found the following article which isn't too out of date.  Unfortunately, it pretty much says nobody knows for sure. 

www.aans.org/Library/Article.aspx?Articleid=12429


Abstract:  2002 Apr 3

Familial Moyamoya Disease in Caucasians

Author(s):   
Sabrina M. Walski-Easton, M.D.,
Ramachandra P. Tummala, M.D.
Ray M. Chu, M.D.
Leslie A. Sebring, M.D.
Eric S. Nussbaum, M.D.

Introduction: Moyamoya disease is characterized by stenosis or occlusion of the internal carotid arteries (ICA) with attempted collateral formation. The disease was originally described in Japanese individuals and seems to be most common in this population. The incidence of familial moyamoya disease may be as high as 10% in Asians, but the occurrence of familial cases in Caucasians is exceedingly rare. We have identified two Caucasian families with more than one member affected by moyamoya disease. Methods: Two Caucasian patients were identified with ischemic strokes from moyamoya disease and a parent who had also suffered from moyamoya disease as well. Their hospital records and imaging studies were reviewed. Results: A 23-year-old Caucasian man presented with a right basal ganglia ischemic stroke. He underwent bilateral extracranial to intracranial (EC-IC) bypass for moyamoya disease. A 43-year-old woman presented with a right hemispheric ischemic stroke and was found to have right ICA occlusion and left ICA stenosis. She was also treated with bilateral EC-IC bypass. Each patient had a parent who had previously undergone EC-IC bypass for moyamoya disease. Both patients of the current generation described here and their parents have been asymptomatic since cerebral revascularization. Conclusions: We describe two rare cases of familial moyamoya disease in Caucasian patients. A detailed family history in all patients with this condition may identify other relatives at risk for complications of the disease. We suggest that careful genetic evaluation of familial cases may provide insights into the cause of this disorder. Additional relatives with histories of cerebral ischemia have been identified, and their evaluation for moyamoya disease is pending. Formal genetic evaluation of the described families is also pending.