Association between NOD2 and autoinflammation presenting as Yellow Nail Syndrome

Abstract

Background: Yellow Nail Syndrome is defined as a triad of lymphedema, respiratory symptoms, and nail discolouration. The precise etiology remains unknown, however it has been reported alongside a broad spectrum of conditions including malignancies, autoinflammatory diseases, and immunodeficiencies. Aim: To highlight the association between defects in the intracellular bacterial sensor gene NOD2 and Yellow Nail Syndrome. Methods: A retrospective review of the patient’s chart was performed, including family history, characteristics, immune laboratory evaluation, and genetics. Results: A 65-year-old female was referred to our centre for lymphedema and bronchiectasis. She had recurrent episodes of pneumonia, cellulitis, and oral ulcers. Bilateral lymphedema on her lower limbs up to the hip and discoloured yellow nails were reported. Given her clinical picture, she was diagnosed with Yellow Nail Syndrome. The immunological evaluation was unremarkable overall, with normal T cell subsets and function and adequate antibody titers. Genetic testing identified a heterozygous mutation in the NOD2 gene, c.2107C>T (p.Arg703Cys), considered a variant of uncertain significance. Conclusion: Heterozygous variants in NOD2 can result in a spectrum of autoimmune and autoinflammatory disorders, including Yellow Nail Syndrome. Statement of novelty: We describe a patient with Yellow Nail Syndrome, presenting with the classic triad of clinical features. Genetic evaluation identified a heterozygous variant in NOD2, which has been extensively associated with several autoinflammatory diseases, but not Yellow Nail Syndrome.