Targeted Next Generation Sequencing Expands Genotype in Patients with PIK3CA-Related Overgrowth Spectrum (PROS)

Background: Disorders of somatic mosaicism (DoSM) are caused by mutations that arise post-zygotically and are present in only a specific part of the body. These mutations alter the function and regulation of key genes in cell proliferation pathways, including the PI3K/AKT/mTOR pathway, and show significant overlap with mutations identified in cancer(McNulty et al. Am J Hum Genet, 2019). PIK3CA-Related Overgrowth Spectrum (PROS) is an umbrella term that encompasses a variety of overgrowth syndromes caused by post-zygotic, somatic gain-of-function PIK3CA mutations with low-level mosaicism (Luks et al. J Pediatr, 2015). The clinical phenotype of PROS is heterogeneous and many tissue types can be affected. This often makes clinical diagnosis challenging. The use of cancer genomics in patients with vascular anomalies may aid in establishing a genetic diagnosis and expand use of targeted medical therapies.