The phenotype and severity of HA20 in our survey differed, even among cases with the same variantof TNFAIP3. HLA alleles affecting T cells are reportedly a factor influencing thephenotypes of Behcet’s spectrum disorders (e.g. recurrent aphthous stomatitis, PFAPA, and BD), including severity and tissue involvement, with the strongest association between HLA and BD (22). The gene discussed is TNFAIP3; the disease is A20 haploinsufficiency.