Infantile Onset Haploinsufficiency of A20 Treated by Infliximab, a Case Report and Brief Review of Literature.

Background: Haploinsufficiency of A20 (HA20) is a rare genetic autoinflammatory syndrome caused by heterozygous loss-of-function variants in TNFAIP3. It typically appears in early childhood with recurrent fevers, mucocutaneous ulcers, gastrointestinal symptoms, and occasional eye involvement. The overlapping features with Behçet disease and other autoinflammatory disorders often make diagnosis challenging. Case Presentation: We describe a 5-year-old girl who developed periodic fevers from age 2, along with oral ulcers, eye redness and swelling, abdominal pain, diarrhea, perianal tenderness, and dysuria. Initial treatments with colchicine and intermittent prednisolone provided little benefit. Whole exome sequencing revealed a likely pathogenic variant in TNFAIP3 (TNFAIP3 Chr6 138197257 138197257 C: NM_001270507.2: (5/9): c.759delC: p. Asp253fs), consistent with a diagnosis of Behçet-like autoinflammatory syndrome (HA20), with additional variants in PIK3R1, HBB, and SERPINA1 possibly modifying the phenotype. Management and Outcome: After the genetic diagnosis, therapy was escalated to infliximab, which led to improvement, this highlights the effectiveness of targeted biologic therapy in refractory pediatric HA20 insufficiency who unresponsive to conventional therapies.