| Background:Mutations in the gene encoding bone morphogenetic protein receptor type 2(BMPR2)are the most common genetic risk factors underlying pulmonary arterial hypertension(PAH).However,the features of PAH-related BMPR2 rare variants remain unclear.We propose that the discrepancy of BMPR2 rare variants landscape between patients with PAH and reference population would be important to address the genetic background of PAH-related variants.Methods:We genotyped BMPR2 rare variants in 670 Chinese patients with pulmonary arterial hypertension.The BMPR2 rare variants were screened in 10,508 reference people from two exome databases.Results:The prevalence of rare BMPR2 variants in patients with PAH was significantly higher compared to the reference population(21.5%,144/670 vs 0.87%,91/10508,p=1.3×10-118).In patients with PAH,49%of identified BMPR2 rare variants were loss-of-function or splicing.These BMPR2 rare variants were only observed in 1%of the reference population(p=9.0×0-12).Arg491,which is absent in the reference population,represented as hot-spot site(14.6%,21/144)in PAH patients.BMPR2 missense mutations in PAH patients were more likely distributed in extracellular ligand-binding domain(ECD,29.7%vs 11.1%,p<0.001).Compared with Non-PAH-related variations,PAH-related missense variants tend to alter the amino acid electric status(51.4%v.s.23.3%,p<0.001).Conclusion:BMPR2 variants located in extracellular ligand-binding domain or altered the amino acid electric status are more pathogenic.Background:A number of genetically mouse models have been generated with a loss-of-function mutation on BMPR2 gene to study the pathogenesis of PAH.However,current mice models may not fully represent the pathology of clinical PAH.Hemodynamic and imageological measurements are difficult to obtain in mice.To understand the role of BMPR2 mutation in the development of PAH,we firstly constructed a novel rat model with BMPR2 hotspot mutation and examined the phenotype.Methods:Using genetic testing,670 IPAH/FPAH cases have been screened for BMPR2 mutation to find the hotspot mutation Arg491.SD rats carrying the heterozygous hotspot mutation were constructed by CRISPR/Cas9.The phenotypic characteristics were compared between BMPR2 mutant and wild-type rats at baseline or exposed to hypobaric hypoxia(50Kpa,10%O2)for 3 weeks.Results:Rats carrying p.R491W mutation were apparently normal at baseline.However,after the hypobaric hypoxia treatment,the mutant rat showed more severe pulmonary vascular remodeling phenotype and RV hypertrophy.Compared to the wild-type littermates,the RVSP and RV/(LV+S)were increased by 12%and 21%respectively in Bmpr2R491W rats.Echocardiographic assessment showed that the RV free wall thickness of Bmpr2R491W rats were 1.23 times that of wild-type rats,the TAPSE and right ventricular outflow tract cardiac output were reduced by 31%and 37%,respectively.The ratio of fully muscularized arteries and the wall thickness of muscularized pulmonary arteries(<75?m in diameter)were greater in Bmpr2R491W rats.Conclusion:We firstly constructed the transgenic rat model with a hotspot missense mutation Bmpr2R491W related to PAH.Bmpr2R491W rats are more susceptible to hypoxia-induced pulmonary arterial hypertension than wild-type rats to be an ideal rodent model to study the molecular mechanism of heritable pulmonary arterial hypertension.Rationale:Pulmonary arterial hypertension(PAH)is a life-threatening disorder predisposed by genetic modifying factors.Rare causal alleles have been found in more than seventeen PAH-susceptible genes,establishing PAH as a genetically heterogenous conditions.Deleterious mutations in bone morphometric protein receptor 2(BMPR2)represent the central genetic risk factor for the heritable case(HPAH),with BMPR2 variants associated with worse hemodynamic compromises and an increased risk of death.Large populations of patients in the idiopathic form(IPAH),the most common form of the disease,exhibit an underlying genetic cause for their conditions.The relative distributions and influences of pathogenic alleles,other than BMPR2,in IPAH clinical presentations are not well-defined.Elucidating the genetic architecture of IPAH cases provides unprecedented potential for the development of novel precision options in disease management.Methods:Next-generation whole exome sequencing was performed in 421 IPAH patients recruited from independent expert centers in China.Rare causal variants in a panel of seventeen known PAH-susceptible genes were analyzed.Clinical,functional and hemodynamic parameters,as well as long-term outcomes were stratified by genetic status.Results:Deleterious variants were identified in 48.7%of the IPAH cases.BMPR2 had the highest mutation frequency(18.5%)in the analysis,followed by GDF2(5.2%)and ACVRL1(5.0%).Variants independent of BMP signaling were also found,including RNF213(3.3%),TBX4(2.4%)and ATP13A3(1.9%)ranking top two in this category.Patients with pathogenic mutations demonstrated a younger age at diagnosis and a male-dominant phenotype,and had significant higher mean pulmonary artery pressures,as well as,pulmonary vascular resistance compared to non-carriers.Clinical characteristics were indistinguishable between individuals bearing mutations within BMP signaling and patients having variants belong to other pathways.BMPR2 mutations failed to predict clinical worsening in patients treated with combination therapy,while male sex and utility of combination therapy were the only significant deteriorate of PAH progression.Conclusions:Assessing the prevalence and clinical relevance of pathogenic variants in seventeen PAH-susceptible genes in a well-defined patient cohort,we advanced the knowledge of the genetic architecture of IPAH populations in China.Our analysis confirmed the roles of deleterious genetic variants in the precipitation and progression of IPAH,by demonstrating mutation carriers posing a younger age of onset and worse clinical presentations.This study also suggests that early diagnosis and combination therapy could modify disease progression mediated by genetic risk factors. |
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