P224: Using Long-Read Sequencing for Genomic and Epigenomic Analysis in Patient-Derived Samples with Somatic IDH1 Mosaicism

Ollier disease (OD) and Maffucci syndrome (MS) are rare cancer susceptibility syndromes characterized by multiple enchondromas. Patients with MS also have vascular anomalies. OD/MS arises in childhood and causes significant morbidity from severe skeletal deformities, pain, and pathological fractures. Approximately 80% of patients with OD/MS have somatic mosaic gain-of-function (GoF) variants in IDH1 and IDH2 genes in their enchondromas and/or vascular anomalies. These variants likely occur early in embryogenesis, leading to a mosaic pattern of disease distribution.