Pulmonary hypertension in children with Down syndrome.

Individuals with Down syndrome (DS) have an increased risk of developing pulmonary hypertension (PH). In this review, we explore the epidemiology and clinical characteristics of PH in the population with DS and examine genetic, molecular and clinical contributions to the condition. The presence of an additional copy of chromosome 21 (trisomy 21) increases the risk of developing PH in children with DS through many mechanisms, including increased hemodynamic stress in those with congenital heart disease, hypoxemia through impaired ventilation to perfusion matching secondary to developmental lung abnormalities, pulmonary hypoplasia from pulmonary vascular endothelial dysfunction, and an increase in pulmonary vascular resistance often related to pulmonary comorbidities. We review recent studies looking at novel biomarkers that may help diagnose, predict or monitor PH in the population with DS and examine current cardiopulmonary guidelines for monitoring children with DS. Finally, we review therapeutic interventions specific to PH in individuals with DS. Contemporary work has identified exciting mechanistic pathways including the upregulation of antiangiogenic factors and interferon activity, which may lead to additional biomarkers or therapeutic opportunities. Throughout the manuscript, we identify gaps in our knowledge of the condition as it relates to the population with DS and offer suggestions for future clinical, translational, and basic science research.