Joint involvement in Noonan syndrome. A retrospective paediatric descriptive study

•In Noonan syndrome, joint symptoms appear during childhood.•Musculoskeletal pain are present in 25 % of the patients and joint stiffness in 14 %.•The knees and the elbows, are the more affected joints.•Treatment with GH and SOS1 mutations was significantly related to the occurrence of musculoskeletal pain.•Villonodular synovitis is severe and more frequently multifocal but rare. Noonan syndrome is a rare genetic disorder characterized mainly by congenital heart disease, occasional intellectual disability, and varied orthopaedic, rheumatological and haematologic anomalies. Despite potentially serious functional consequences, joint involvement has been rarely studied in the literature. Our objective was to perform a retrospective study evaluating the prevalence and characteristics of joint involvement in Noonan syndrome. We recorded articular symptoms, including their type and frequency, in patients with Noonan syndrome followed up in French hospitals. Patients were included if the diagnosis was confirmed before the age of 20 based on the van der Burgt criteria or genetic analysis. Data are presented as frequencies or medians (ranges), and patient groups were compared using chi-square or Fisher tests. Seventy-one patients were included from 4 centres. The average age was 12.5 years (range: 2–36). Musculoskeletal pain was found in 18 patients (25%) and joint stiffness in 10 (14%) located in the wrists, elbows, ankles, knees and hips, which was usually bilateral. Only one destructive form was described (multiple villonodular synovitis and a giant cell lesion of the jaw). There were no cases of systemic lupus erythaematosus (SLE) or other autoimmune arthritis. Raynaud's phenomenon was observed in 3 patients. Only 50% of joint complaints led to additional exploration. SOS1 mutations (P