Pettersson et al. (2017) recently documented two patients, with the same IFIH1 mutation as our finding, presenting clinical features of both SMS and severe systemic lupus erythematosus (SLE). Very recent report from de Carvalho et al. (2017) revealed another five patients with the clinical phenotype of classic SMS caused by two novel mutations in IFIH1. The clinic features and genetic mutations of classic SMS and atypical SMS are summarized in Table 1. The gene discussed is IFIH1; the disease is Smith-Magenis syndrome.