Noonan-like syndrome with anagen hair loss is a RAS pathology and is characterized by craniofacial features resembling Noonan syndrome, a spectrum of cardiovascular abnormalities, cognitive deficits and behavioral distorders, short stature usually associated with growth hormone deficiency, a unique combination ectodermal disorders. It results from a missense variant (c.4A>G, c.Ser2Gly) in the SHOC2 gene, located on chromosome 10q25, which encodes a protein that facilitates signaling through the RAS mitogen-associated protein kinase pathway, triggering a number of cellular processes. The prevalence of the syndrome is less than 1 in 1,000,000 (worldwide). Evidence has been obtained that disturbances in the level of expression and activation of the Ras family signaling pathway and its downstream kinases, such as Raf/MEK/ERK1–2, contribute to the pathogenetic mechanisms of the development of autoimmune diseases. Description of a clinical case. We present a previously undescribed clinical case of the development of juvenile arthritis associated with Crohn’s disease in a 13-year-old girl with Noonan-like syndrome with hair loss in the anagen phase. At birth, the patient was diagnosed with a congenital heart defect (multiple atrial septal defect), corrected at 4 years, articular syndrome debuted at 8 years 4 months, intestinal syndrome at 10 years 4 months. Genetic analysis was carried out only at 10 years 7 months, DNA sequencing results were obtained and a pathogenic variant of the nucleotide sequence of the SHOC2 gene was identified in a heterozygous state (c.4A>G, p.Ser2Gly). As a result of the analysis of clinical data, laboratory and instrumental studies, a diagnosis was made: “Juvenile arthritis (pauciarticular variant) associated with Crohn’s disease (ulcerative bauginitis, ulcerative ileitis, catarrhal jeunitis, aphthous left-sided colitis, erosive gastritis). Noonan-like syndrome with hair loss in the anagen stage 1. Hypopituitarism. Partial growth hormone deficiency. Condition after ASD repair.” The girl received treatment: a course of glucocorticosteroids (methylprednisolone) with gradual withdrawal, methotrexate, adalimumab and mesalazine with positive dynamics. Conclusion. Pediatricians need to remember the possibility of developing autoimmune diseases in children with NPS, the need for their early diagnosis, timely referral to specialists and adequate therapy. © 2024, Global Media Technologies. All rights reserved.