Leri's pleonosteosis, a congenital rheumatic disease, results from microduplication at 8q22.1 encompassing GDF6 and SDC2 and provides insight into systemic sclerosis pathogenesis.

Our work identifies the genetic cause of LP in these two families, demonstrates the phenotypic range of the condition, implicates dysregulation of extracellular matrix homoeostasis genes in its pathogenesis, and highlights the link between TGF-β/SMAD signalling, growth/differentiation factor 6 and syndecan-2. We propose that LP is an additional member of the growing 'TGF-β-pathies' group of musculoskeletal disorders, which includes Myhre syndrome, acromicric dysplasia, geleophysic dysplasias, Weill-Marchesani syndromes and stiff skin syndrome. Identification of a systemic sclerosis-protective SDC2 variant lays the foundation for exploration of the role of syndecan-2 in systemic sclerosis in the future.