EPB42 and histiocytic sarcoma: The former has a sensitivity of 93% and specificity of 98% for the diagnosis of HS,11 and the latter is more specific for protein 4.2– and ankyrin‐deficient HS, but less specific for asymptomatic and mild HS, and is thus unsuitable for determining the type of membrane protein deficiency in approximately 10% of HS patients.15 Gene mutations in HS are scattered, and no specific mutation sites suitable for screening have yet been identified.