In the summer of 2023, HAE International (HAEi) and the US HAE Association (HAEA) enlisted 31 HAE with normal C1INH (HAE-nC1INH) global experts to synthesize our current knowledge in the area in order to present a best practice approach to the diagnosis and management of HAE-nC1INH. This evidence concerns the gene SERPING1 and hereditary angioedema.