Background and Aims Autoimmune dysfunction has been described in patients with Noonan Syndrome (NS). Till date, 9 patients with systemic lupus erythematosus (SLE) and NS have been reported. However, exact relationship between SLE and NS is not known.

Methods To describe the clinical presentation of a child with SLE and NS.

Results A 10-years-old boy presented with fever, gradually progressive dyspnoea, pain in bilateral elbow and knee joints for 8 months. His past and family history was normal. Weight and height were <−3 z-score for his age. He had a long face with relatively large ears, down slanting palpebral fissure and livedo reticularis over lower limbs. Grade III ejection systolic murmur was present at pulmonary area along with loud second heart sound. He had hypertonia with brisk deep tendon reflexes in bilateral lower limbs, bilateral ankle clonus and extensor plantar response.

Investigations revealed anaemia, thrombocytopenia, leucopenia, elevated acute phase reactants and aPTT prolongation. His antinuclear antibody was positive by indirect immunofluorescence (4+ homogenous), anti-double stranded deoxyribonucleic acid was elevated and direct coomb test and lupus anticoagulant were positive along with low serum complement 3 level. Echocardiography revealed mitral valve prolapse and mitral regurgitation. Magnetic resonance imaging of brain revealed chronic lacunar infarct in medial aspect of right thalamus.

A diagnosis of SLE, APLA and NS was made and treatment with oral prednisolone, hydroxychloroquine, acetyl salicylate and low molecular weight heparin was initiated.

Conclusions Autoimmune conditions including SLE are being increasingly described in patients with NS requiring close monitoring and long term follow up.