Background: Paediatric-onset idiopathic/hereditary pulmonary arterial hypertension (IPAH/HPAH) is partially linked to genetic factors that may also affect treatment response and outcome. The relation between clinical characteristics and pathogenicity of gene variants in childhood IPAH/HPAH is still not well understood.
Methods: We retrospectively analyzed IPAH/HPAH paediatric patients aged between 3 months and 18 years under follow-up at a large tertiary referral center. Whole-exome sequencing focused on PAH high-risk genes was performed in all patients. Pathogenicity grading of gene variant sites was assessed using ClinVar and population frequencies. The association between gene variants and death was studied using Cox proportional multivariate models.
Results: Overall, 129 patients (54.3% females; 91.5% on PAH therapy) with a median age at diagnosis of 6.8 (IQR 3.4-10.7) years were included. A relevant PAH gene variant was detected in 95 patients (73.6%). The most common variants were in the BMPR2 (n = 43, 3%) gene. Over a median follow-up period of 27.6 months, 26 children died. The presence of a likely pathogenic genetic variant was significantly associated with survival (HR: 3.56, p = 0.005) on multivariable Cox analysis. The number of PAH-specific drugs at presentation was associated with better survival in the cohort with pathogenic variants (p = 0.02).
Conclusions: Pathogenic/likely pathogenic genetic variants are prevalent in children with PAH and are related to a worse prognosis irrespective of other recognized risk factors in this population. Combination PAH therapy was associated with superior prognosis in children with pathogenic variants or BMPR2 variants. Therefore, proactive medical therapy should be employed in this population.
Keywords: genetic; outcome; paediatric; pathogenic; pulmonary arterial hypertension.