• Matina Prapa, Mauro Lago-Docampo, Emilia M Swietlik, David Montani, Mélanie Eyries, Marc Humbert, Carrie L Welch, Wendy K Chung, BergerRolf M FRMF0000-0002-4385-5784Centre for Congenital Heart Diseases, Pediatric Cardiology, Beatrix Children's Hospital, and., Harm Jan Bogaard, Olivier Danhaive, Pilar Escribano-Subías, Henning Gall, Barbara Girerd, Ignacio Hernandez-Gonzalez, Simon Holden, David Hunt, Samara M A Jansen, Wilhelmina Kerstjens-Frederikse, David G Kiely, Pablo Lapunzina, John McDermott, Shahin Moledina, Joanna Pepke-Zaba, Gary J Polwarth, Gwen Schotte, Jair Tenorio-Castaño, ThompsonA A RogerAAR0000-0002-0717-4551Department of Infection, Immunity, and Cardiovascular Disease, University of Sheffield, Sheffield, United Kingdom.Sheffield Pulmonary Vascular Disease Unit, Royal Hallamshire Hospital, Sheffield, United Kingdom., John Wharton, Stephen J Wort, Karyn Megy, Rutendo Mapeta, Carmen M Treacy, Jennifer M Martin, Wei Li, Andrew J Swift, Paul D Upton, Nicholas W Morrell, Stefan Gräf, Diana Valverde, NIHR BioResource for Translational Research–Rare Diseases, National Cohort Study of Idiopathic and Heritable PAH, and PAH Biobank Enrolling Centers’ Investigators.
• Department of Medicine and.
• Am. J. Respir. Crit. Care Med. 2022 Dec 15; 206 (12): 152215331522-1533.

AbstractRationale: Despite the increased recognition of TBX4 (T-BOX transcription factor 4)-associated pulmonary arterial hypertension (PAH), genotype-phenotype associations are lacking and may provide important insights. Objectives: To compile and functionally characterize all TBX4 variants reported to date and undertake a comprehensive genotype-phenotype analysis. Methods: We assembled a multicenter cohort of 137 patients harboring monoallelic TBX4 variants and assessed the pathogenicity of missense variation (n = 42) using a novel luciferase reporter assay containing T-BOX binding motifs. We sought genotype-phenotype correlations and undertook a comparative analysis with patients with PAH with BMPR2 (Bone Morphogenetic Protein Receptor type 2) causal variants (n = 162) or no identified variants in PAH-associated genes (n = 741) genotyped via the National Institute for Health Research BioResource-Rare Diseases. Measurements and Main Results: Functional assessment of TBX4 missense variants led to the novel finding of gain-of-function effects associated with older age at diagnosis of lung disease compared with loss-of-function effects (P = 0.038). Variants located in the T-BOX and nuclear localization domains were associated with earlier presentation (P = 0.005) and increased incidence of interstitial lung disease (P = 0.003). Event-free survival (death or transplantation) was shorter in the T-BOX group (P = 0.022), although age had a significant effect in the hazard model (P = 0.0461). Carriers of TBX4 variants were diagnosed at a younger age (P < 0.001) and had worse baseline lung function (FEV1, FVC) (P = 0.009) than the BMPR2 and no identified causal variant groups. Conclusions: We demonstrated that TBX4 syndrome is not strictly the result of haploinsufficiency but can also be caused by gain of function. The pleiotropic effects of TBX4 in lung disease may be in part explained by the differential effect of pathogenic mutations located in critical protein domains.

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