ROSAH syndrome: childhood-onset arthritis, hand deformities, uveitis, and splenomegaly

A 33-year-old man was referred to our internal medicine department after an ophthalmic examination revealed a bilateral granulomatous anterior and intermediate uveitis with papillitis (figure A) associated with retinal dystrophy features (figure B). The patient had been experiencing decreased vision for several months and had a history of childhood-onset bilateral arthritis, involving proximal and distal interphalangeal and metacarpophalangeal joints. His sister, mother, and uncle were previously treated for idiopathic uveitis and papillitis. He reported recurrent headaches and anhidrosis. Physical examination revealed hand deformities (figure C) with nail dystrophy and melanonychia (figure D) and an enlarged spleen (20 cm). X-rays showed erosions of the proximal and distal interphalangeal joints (figure E). Laboratory investigations found elevated C-reactive protein (86 mg/L, normal range <5 mg/L), but normal white blood cell counts (normal count, 6.48 g/L). Thorough investigation for infectious diseases and autoimmune biomarkers were negative. Because of the familial context and a recent observation of a similar phenotype, we did targeted sequencing of the ALPK1 gene, which encodes α kinase 1, in the patient and his sister. We found the heterozygous missense variant (p.Thr237Met) in the patient and his sister, which has previously been reported to cause retinal dystrophy, optic nerve oedema, splenomegaly, anhidrosis, and headache (ROSAH) syndrome. Treatment was started with intravenous tocilizumab at a dose of 8 mg/kg every 4 weeks. ALPK1 is a recently described intracellular pattern-recognition receptor, which senses metabolites of several bacteria. ROSAH syndrome is an autoinflammatory disease with a highly variable phenotype, including (in addition to the ROSAH-defining features) recurrent fever, cytopenias, dental and nail abnormalities, sicca syndrome, and meningeal inflammation on brain MRI. To date, about 60 people have been described as having the syndrome worldwide. The best treatment remains unknown, but biologics targeting tumour necrosis factor, interleukin (IL)-1, and IL-6 have shown efficacy in suppressing systemic inflammation. This large spectrum of inflammatory features can mimic Blau syndrome; however, a rash is common in this disease, whereas it has not been described in ROSAH syndrome.