Inborn errors of immunity affecting the MHC class I pathway for antigen presentation.

Inborn errors of immunity affecting the major histocompatibility complex (MHC) class I pathway for antigen presentation represent a rare group of human disease syndromes. Here, we review symptoms associated with such conditions, which manifest as chronic respiratory infections, granulomatous skin lesions, and related severe symptoms. We highlight the potential for misdiagnosis with autoimmune conditions such as granulomatosis with polyangiitis and emphasize the necessity of infection-focused treatment, given the risks associated with immunosuppressive therapy. Furthermore, we present novel long-term follow-up data on TAP-deficient patients, revealing new insights into disease progression, including an increased risk of skin cancer and severe herpesvirus infections. Additionally, we discuss cases of a few individuals with significant MHC class I deficiency who remain largely asymptomatic, underscoring the variability in clinical presentation. Our findings emphasize the importance of further genetic research and immunopathological analysis to identify predictive markers and optimize individualized treatment approaches. Long-term patient surveillance remains critical to understanding late-onset complications and refining clinical management strategies.