Upon activation of this pathway, serum mannose-binding lectin (MBL) can bind to viral surface glycoproteins, thereby initiating downstream activation reactions and exerting antiviral effects (29, 30).Case reports have documented patients with Ficolin-3 deficiency presenting severe primary immunodeficiency, accompanied by bacterial infections and neurological complications (31, 32). The gene discussed is FCN3; the disease is inborn error of immunity.