We aim to phenotype and genotype a cohort of newly described patients with Moyamoya disease who are of Polynesian or Māori (indigenous peoples of New Zealand) ancestry.

Moyamoya disease (MMD) is a progressive occlusive cerebral arteriopathy. It is reported predominantly in East Asian Cohorts (Korean, Japanese and Chinese). Most of these people carry the p.R4810K variant in the RNF213 gene. However, this variant has not been seen when looked for in other ethnic groups including those from South-East Asia. No such genetic studies have been undertaken in Pacific Island or Māori peoples.

The pattern of collateral vessel formation seen on angiography is determined by the site of occlusion. In classical MMD the occlusion occurs distal to the anterior choroidal artery giving rise to the “moyamoya / puff of smoke” appearance of collaterals in the basal ganglia.

Electronic hospital discharge records containing the words Moyamoya disease or syndrome were reviewed from 2008 to 2023. Patients were excluded if they were deceased or had other causes of cerebral arteriopathy (e.g. trisomy 21). Phenotypic data was collected on the remaining patients and their DNA was sent for whole genome sequencing (results pending).

This study draws on a population of 1.7 million people. This initially yielded 63 patients. A total of 35 patients with MMD were found after applying exclusion criteria. Of these, 19 had Māori/Polynesian or South-East Asian ancestry (8 Māori or Cook Islands Māori, 9 Polynesian and 2 South-East Asian). The mean age of the cohort (SD) was 39.6 years (7.4), range 9 to 68 years. Polynesian and Māori patients had a unique pattern of collateral formation different from typical MMD due to more proximal terminal ICA occlusion.

We describe a novel cohort of patients with occlusive arteriopathy who are of Polynesian, Māori and South-East Asian ancestry.