Abstract
We report a novel genetic variant in a patient with treatment-resistant peripheral pulmonary artery stenosis (PPS) and progressive pulmonary arterial hypertension (PAH). A premature infant was diagnosed with bilateral PPS requiring multiple surgical reconstructions and interventional procedures with refractory proximal stenoses. Despite adequate anatomic repair preserving nearly all right lung segments, the child developed progressive PAH with elevated pressures in preserved segments out of proportion to residual obstruction. Genetic evaluation revealed a de novo heterozygous variant in FGD5, a critical regulator of VEGF signaling essential for pulmonary vascular development and homeostasis. We propose that FGD5 haploinsufficiency could disrupt endothelial function during development, leading to aberrant vascular patterning. This dysfunction may lead to PPS and ongoing endothelial dysfunction contributing to PAH. This represents a potential novel genetic cause of PPS with PAH, expanding the understanding of critical regulators in pulmonary vascular development and pathology. Comprehensive genetic evaluation in treatment-resistant pulmonary vascular disease may identify novel mechanisms and eventually guide personalized therapeutic approaches through enhanced genotype-phenotype correlation.