Genetics and Genomics of Pediatric Pulmonary Arterial Hypertension

Pulmonary arterial hypertension is a rare disease with high mortality despite recent therapeutic advances. The disease is caused by both genetic and environmental factors, and likely gene x environment interactions. While PAH can manifest across the lifespan, pediatric-onset disease is particularly challenging because it is frequently associated with a more severe clinical course and comorbidities including lung/heart developmental anomalies. In light of these differences, it is perhaps not surprising that emerging data from genetic studies of pediatric-onset PAH indicate that the genetic basis is different than that of adults. There is a greater genetic burden in children, with rare genetic factors contributing to at least 36% of pediatric-onset idiopathic PAH (IPAH) compared to ~11% of adult-onset IPAH. De novo variants are frequently associated with PAH in children, and contribute to at least 15% of all pediatric cases. The standard of medical care for pediatric PAH patients is based on extrapolations from adult data. However, the increased etiologic heterogeneity, poorer prognosis and increased genetic burden for pediatric-onset PAH calls for a dedicated pediatric research agenda to improve molecular diagnosis and clinical management. A genomics-first approach will improve the understanding of pediatric PAH and how it is related to other rare pediatric genetic disorders.