Genetic Pedigree And Animal Model Study Of BMPR2 Mutation Leading To Pulmonary Hypertensio

BACKGROUND:Pulmonary hypertension is a malignant disease with a poor prognosis and is strongly hereditary.Domestic and foreign guidelines for the diagnosis and treatment of pulmonary hypertension recommend genetic testing for patients with idiopathic and familial pulmonary hypertension,and provide genetic counseling for patients’ families.METHODS:We confirmed a hereditary pulmonary hypertension family in the genetic clinic of Fuwai Hospital,with a total of 2 patients in the family.We collected samples from 13 family members,tested for BMPR2 gene mutations,and provided genetic counseling to family members.RESULTS:The family was a 29-year-old female with average pulmonary artery pressure 98mmHg,pulmonary vascular resistance 27Wood Unit,and significantly enlarged right heart.The first-generation sequencing found that the proband carried a completely new BMPR2 mutation(c.1229G>A),which ACMG rated as pathogenic.The younger brother of the proband also had pulmonary hypertension,which was estimated to be 66 mmHg.Other healthy people in the family do not carry the mutation,and the BMPR2 mutation is co-isolated from the pulmonary hypertension phenotype.If the lover of the brother of the prospector becomes unexpectedly pregnant,we provide genetic testing and genetic counseling for the fetus,and through prenatal testing,it is determined that the fetus does not carry the genetic mutation.CONCLUSION:This familial pulmonary hypertension is caused by BMPR2 mutation.Genetic testing clarified the cause of the patient,guided family fertility,and provided an important basis for the precise treatment of pulmonary hypertension.BACKGROUND:Mutations in the BMPR2 gene are the most common single causative factor in cases of hereditary pulmonary arterial hypertension.Previous studies have mostly used knockout or truncated mutations to construct animal models of Bmpr2,and in vivo animal studies of Bmpr2 missense mutations are lacking.To better model the role of missense mutation Bmpr2 in HPAH,we constructed a new BMPR2 hotspot mutant rat.METHODS:According to the results of our group’s previous genetic study,the BMPR2 p.R491W/Q mutation rate was the highest in 670 patients with pulmonary arterial hypertension.We used CRISPR/Cas9 technology to single-base edit the rat Bmpr2 genomic region and targeted knock-in of the hotspot mutation c.C1471T in patients with pulmonary arterial hypertension to construct Bmpr2 p.R491W mutant rats by Ultrasound,catheterization and pathology experiments were performed to confirm whether the rat model would mimic the human phenotype of pulmonary hypertension.RESULTS:In the results of our preliminary experiments,it was observed that Bmpr2+/R491W mutant rats did not cause spontaneous pulmonary hypertension up to 12 months of age.Three weeks after administration of hypoxia(10%O2),mPAP exceeded 25 mmHg in both wild-type and mutant rats compared to baseline rats.mPAP/PET ratio was 25%lower and right ventricular outflow tract width was 24%wider in mutant rats compared to wild-type rats,with no difference in haemodynamics.CONCLUSIONS:After hypoxia induction,mutant rats did not exhibit a more severe pulmonary hypertension phenotype compared to wild-type rats,suggesting that hypoxia is not a double whammy factor in mutant rats.BACKGROUND:Pulmonary arterial hypertension is a class of malignant,lethal diseases and there is a lack of animal models that realistically mimic the characteristics of patients with PAH.METHODS:Ultrasound phenotypic screening assays,catheterization for hemodynamic changes and histopathological characterization of the mutant rats were performed continuously,over a long period of time and at different months.RESULTS:After 12 generations of breeding,15%of the offspring of Bmpr2+/R491W mutant rats developed pulmonary hypertension spontaneously at 3 months of age.Compared to rats from the same litter without pulmonary hypertension,the rats had significantly higher mean pulmonary artery pressure(17.8±1.2 mmHg vs 37.7±8.5 mmHg),a 1-fold increase in right anterior heart wall thickness(RVAW;d)(0.8±0.1 mm vs 1.6±0.3 mm)and a 1.26-fold widening of the right ventricular outflow tract(RVOT)(3.0±0.4(3.0±0.4 mm vs.6.8±0.1 mm).Pathological examination showed significant pulmonary vascular remodelling and greater myelination of small pulmonary vessels in the affected rats.Conclusion:The Bmpr2+/R491W mutant rats developed pulmonary hypertension spontaneously in 15%of the rats at 3 months of age,and the mutation epistasis and pathological phenotype were close to those of the patients,which better mimicked the pathogenesis of patients with hereditary pulmonary hypertension and provided an important animal model for the study of the pathogenesis of BMPR2 mutation.