Pulmonary hypertension in patients carrying FLNA loss-of-function variants

Background: Pulmonary hypertension (PH) is an unusual complication of X-linked disease caused by loss-of-function (LOF) variants in the filamin A (FLNA) gene. Patients with FLNA LOF may also present dysmorphic facial features, aortic dilation, thrombopenia, and periventricular nodular heterotopia (PVNH).

Methods: We reported clinical, functional, radiologic, and hemodynamic characteristics of patients with FLNA LOF variants and PH from the French PH Network.

Results: Nine patients were identified with a female to male ratio of 8:1. PH was diagnosed at a median age of 36 [0-69] years. Associated conditions included epilepsy (n=5), PVNH (n=7), valvular heart disease (n=8), congenital heart diseases (n=4), thrombocytopenia (n=4), and hyperlaxity (n=4). Right heart catheterisation confirmed moderate-to-severe precapillary PH with a median mPAP of 33 [22-49] mmHg and PVR of 4.7 [2.4-8.0] WU. The DLCO was markedly decreased (48 [22-64] %pred) and five patients had obstructive ventilatory disorder. High-resolution CT showed heterogeneous parenchyma (n=8), emphysema (n=3), presence of a peripheral hyperclear band (n=3) and aortic ectasia (n=4). Pathologic assessment available in one patient revealed significant remodelling of small pulmonary arteries, interstitial edema, and irregular alveoli shapes. During follow-up, three patients died, including two from right heart failure. No patient died from aortic rupture.

Conclusions: Precapillary PH, likely due to multiple mechanisms, may complicate the course of patients with LOF FLNA variants and may be the presenting symptom leading to diagnosis. The combination of PH with parenchymal involvement and extrapulmonary symptoms (epilepsy, congenital heart diseases, valvular and aortic involvement, thrombocytopenia) should prompt genetic screening for FLNA.