AbstractBackgroundCOPA syndrome is a recently described and rare monogenic autosomal dominant disease caused by heterozygous missense mutations in the Coatomer Protein Subunit alpha (COPA) gene that encodes the alpha subunit of coat protein complex I (COPI). Its main clinical manifestations are inflammatory lung disease, arthritis, and renal disease. The development of inflammation in COPA syndrome maybe due to abnormal autophagic response and abnormal activation of type I interferon pathway. To date, 59 cases of COPA have been reported worldwide.MethodsIn this case, Trio‐whole exome sequencing was employed in the proband and her parents to identify the underlying genetic cause. COPA variant were detected and the clinical presentation of the patient was described.ResultsHerein, we report a case of a 5‐year‐old girl with COPA syndrome who presented with symptoms of arthritis combined with Anti‐neutrophil Cytoplasmic Antibody (ANCA) associated vasculitis (AAV), and progressive renal decline with minimal pulmonary involvement. Trio‐whole exome sequencing was performed which revealed a novel heterozygous likely pathogenic variation in the COPA gene (c.679C>T,p.Arg227Cys), which was maternally inherited. Her mother was a heterozygote, but she had no phenotypic manifestations. No other mutations associated with the clinical phenotype were identified.ConclusionThe present identification and characterization of a novel mutation expands the genotypic spectra of the COPA syndrome and provide reference data to guide future clinical diagnosis and treatment of COPA syndrome.