Background: The RAS/MAPK disorders [Noonan syndrome, cardiofaciocutaneous (CFC) syndrome, Costello syndrome, and Leopard syndrome] are heterogenous conditions with phenotypic overlap. Their orthopaedic manifestations are not well defined, and their phenotypic similarity makes differentiating them difficult.
Methods: We prospectively evaluated 60 individuals: 26 with Noonan syndrome, 32 with CFC syndrome, and 2 with Costello syndrome. Each individual underwent a structured orthopaedic history and physical evaluation by an orthopaedic surgeon, and a syndromic evaluation by a geneticist.
Results: All groups had a high prevalence of scoliosis (8/26 Noonan syndrome, 8/32 CFC syndrome, and 1/2 Costello). Those with Noonan syndrome or CFC syndrome had a high instance of serious cervical spine disorders, including cervical stenosis, Arnold-Chiari malformation, and syringomyelia in the Noonan syndrome individuals and hydrocephalus, cervical stenosis, torticollis, and Arnold-Chiari in the CFC syndrome individuals. Noonan syndrome manifestations included chronic pain (n=21), pes planus (n=11), pes cavus (n=5), hip contractures (n=5), hand dysfunction (n=3), and hip dysplasia (n=2). Manifestations of CFC syndrome included pes planovalgus (n=20), knee flexion contractures (n=7), hip dysplasia (n=5), elbow flexion contractures (n=4), pedal calluses (n=4), toe crowding (n=4), and hip contractures (n=4). Individuals with Costello syndrome had shorter stature than the other groups and were prone to have hand contractures.
Conclusions: Orthopaedic manifestations are frequent and diverse in Ras/MAPK disorders and can be used in phenotypic differentiation between these disorders.
Level of evidence: II.