Moreover, some evidence of dysfunctional NO regulation in MMD patients exists: Biallelic variants in the gene GUCY1A3 encoding a NO receptor have been shown to cause MMD associated with achalasia in European patients (Herve et al., 2014; Wallace et al., 2016), and recently, biallelic variants in NOS3 were identified in two consanguineous probands with moyamoya angiopathy (Guey et al., 2023). Here, NOS3 is linked to Moyamoya disease.