Abstract WP234: Intracranial Vasculopathy Patterns of RNF213 R4810K Carriers: Does Anatomical Difference Make a Clinical Difference?

Abstract

Introduction: The 2021 revised diagnostic criteria of Moyamoya’s disease (MMD) of Japan more emphasize terminal ICA involvement than 2012 version. Accordingly, there is still ambiguity about whether MCA steno-occlusion with intact ICA qualifies as MMD. Also, basal collateral is mandated in both versions, while its specificity and sensitivity for MMD remain uncertain. Although the discovery of RNF 213 R4810K variant gave hope for further insight into MMD, its diagnostic role is limited by scarce data on associated vasculopathy pattern. Methods: Patients with intracranial vasculopathy tested for RNF213 genotype between September 2017 and 2022 and positive for R4810K were included. They were classified by two anatomical features of vasculopathy in the latest angiographic image: 1) steno-occlusive degree of ICA and MCA, 2) laterality. The resulting classification composes 3 main and 6 subgroups: A) No involvement. B) MCA involvement and intact ICA, bilaterally (B1) or unilaterally (B2). C) ICA involvement, bilaterally (C1), unilaterally (C2), or unilaterally with contralateral MCA involvement (C3). Their demographic and clinical factors were compared, and fulfillment for MMD by 2012 and 2021 criteria was assessed. Results: Among 240 eligible patients, 84 (35.9%) and 33 (14.1%) did not meet 2021 and 2012 criteria. Notably, though group B showed high basal collateral prevalence of over 80%, all (100%) and 25 (36.8%) of them did not fulfill 2021 and 2012 criteria by ICA and MCA parameters. This group showed no significant contrast in demographic, conventional stroke risk factors and hemorrhagic or ischemic stroke prevalence from those with ICA involvement. Conclusions: Despite their clinical and demographic similarities, a notable number of RNF213 R4810K carriers do not meet MMD criteria due to anatomical features, mainly when ICA involvement is absent. Revising the criteria of MMD to incorporate RNF213 R4810K positivity should be considered to address its weakness.