Encoding Bone Morphogenetic Protein Receptor Research Articles

Clinical and hemodynamic phenotype of BMPR2 variation carriers with pulmonary arterial hypertension: A systematic review and a call to action

Background: Carriers of variations in the gene encoding bone morphogenetic protein receptor type 2 (BMPR2∆) are at high risk for severe pulmonary arterial hypertension (PAH+). Aim: To define the clinical and hemodynamic phenotype of BMPR2∆/PAH+ patients. Methods: We performed a systematic review encompassing observational data until July 2019 about BMPR2∆ and confirmed PAH diagnosis. According to international clinical guidelines, we aimed to determine the clinical and hemodynamic phenotype of BMPR2D/PAH+ patients. We also explored functional assessment and risk stratification. PROSPERO ID CRD42019124324. Results: We included 54 reports with 6,668 PAH+ patients, 1,220 were BMPR2∆/PAH+ with an allele frequency within studies ranging from 8.8% to 24.9%. Female sex was predominant, and age at diagnosis ranged from 32.2 to 46.2 years. We observed the occurrence of BMPR2∆ across all PAH clinical classifications, except for schistosomiasis. BMPR2∆ correlated with severity signs and symptoms in PAH, poor functional class, severe pulmonary hypertension with elevated pulmonary vascular resistance, and low cardiac index and output. The clinical and hemodynamic missing data ranged between 28%-49% and 50%-65%, respectively. Conclusion: BMPR2∆/PAH+ patients present a phenotype with high mortality risk. The clinical triad of dyspnea, syncope, and hemoptysis could suggest BMPR2∆/PAH+. However, poor clinical and hemodynamic characterization hinders translating the benefits of genomic analyses to the clinical setting.

BMPR2 variants in pulmonary arterial hypertension. Are they really worrisome?

Abstract Background Pulmonary arterial hypertension (PAH) is a rare and severe disease. The discovery of the gene encoding Bone Morphogenetic Protein Receptor Type 2 (BMPR2) in 2000 was the first evidence of an association between genetics and PAH. BMPR2 mutation carriers are younger and have higher haemodynamic severity, determining higher risk than sporadic cases. In the last few years, novel genetic variants have been identified. The risk of mortality of the currently known mutations is scarce. Purpose To describe the role of gene variants regarding long-term survival in a cohort of PAH patients. Methods We included patients diagnosed with PAH between January 2011-December 2020, following the ESC/ERC Guidelines recommendations. At least one genetic study was available in included individuals. Pulmonary venooclusive disease, PAH associated with congenital heart disease, or connective tissue disorders were excluded. Three groups were compared: no mutation, BMPR2 carriers and other genetic variants. Comparison of qualitative and quantitative variables was done by Chi-square test and ANOVA test, respectively. Crude and adjusted Log-rank test was performed for the evaluation of mortality. Results 361 were finally included. The most frequent gene variant was BMPR2. Among the eight other gene variants, there were 2 cases of KCKN3, 2 of ACVRL1, and 1 case of KCNA5, TBX4, CPS1, and GDF2. BMPR2 and the rest of mutation carriers were younger at diagnosis and had worse haemodynamic parameters than non-carriers. Nevertheless, these patients tended to perform higher distances in the 6-minute walk test. Interestingly, BMPR2 patients had higher DLCO values at diagnosis (table). After 104.1±77.2 months of follow-up, there was a tendency for BMPR2 carriers toward lower crude free survival of mortality or lung transplantation. Nevertheless, this survival benefit disappears when adjusted by age (Table, figure). Conclusions The diagnostic yields of genetic analysis for pathogenic or likely pathogenic variants in idiopathic PAH are approximately 11%. BMPR2 is the most frequent causal gene. These patients are associated with marked haemodynamic impairment. Nevertheless, its younger age probably determines the better long-term results regarding mortality or lung transplantation observed when comparing these results with sporadic patients or those carrying other mutations. Funding Acknowledgement Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Rio Hortega grant. Instituto de Salud Carlos III (ISCIII), Ministry of Science and Innovation, Spanish Government.

The role of genomics and genetics in pulmonary arterial hypertension.

[No abstract. Showing first paragraph of article]Although pulmonary hypertension (PH) had been recognised for centuries, it was not until the invention of cardiac catheterisation in the 1950s that enabled an accurate gene encoding bone morphogenetic protein receptor type 2, in patients with familial and clinical diagnosis. The discovery of heterozygous germline mutations in BMPR2, the idiopathic forms of pulmonary arterial hypertension (PAH) was another breakthrough in understanding the disease and initiated a new era in care of patients with this condition.

The features of rare pathogenic BMPR2 variants in pulmonary arterial hypertension: Comparison between patients and reference population

BackgroundMutations 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. MethodsWe 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. ResultsThe 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 × 10−12). 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% vs 23.3%, p < 0.001). ConclusionsBMPR2 variants located in extracellular ligand-binding domain or altered the amino acid electric status are more pathogenic.

Clinical characteristics and survival of Chinese patients diagnosed with pulmonary arterial hypertension who carry BMPR2 or EIF2KAK4 variants

BackgroundVariants in the gene encoding bone morphogenetic protein receptor type II (BMPR2) are the most common genetic cause of pulmonary arterial hypertension (PAH), whereas biallelic variants in the eukaryotic translation initiation factor 2 alpha kinase 4 gene (EIF2AK4) are described in pulmonary veno-occlusive disease/pulmonary capillary haemangiomatosis (PVOD/PCH). Racial background may influence the clinical characteristics of patients diagnosed with PAH or PVOD/PCH. Here, we compared the clinical characteristics and survival between patients with BMPR2 variants or EIF2AK4 variants in a Chinese population.MethodsHeterozygous variants in BMPR2 and homozygous or compound heterozygous biallelic EIF2AK4 variants predicted to be deleterious were identified as potentially causal. Clinical and radiological data were collected and analysed. The primary outcomes were death or lung transplantation. Hazard ratios (HRs) for death or transplantation associated with the presence of BMPR2 or biallelic EIF2AK4 variants were calculated using Cox proportional hazards models to analyse patient survival.ResultsTwo hundred thirty-two patients with PAH were enrolled for genetic testing, and PAH patients with associated conditions were excluded from the study. Forty-five patients with BMPR2 variants and 11 patients with biallelic EIF2AK4 variants were recruited. PAH patients with BMPR2 or biallelic EIF2AK4 variants presented symptoms at the ages of 25.57 ± 10.17 years and 31.6 ± 9.38 years, respectively. The whole group of patients showed female dominance either with BMPR2 variants or biallelic EIF2AK4 variants. Specific radiological abnormalities are more prominent in EIF2AK4 variant carriers but can also be found in some patients with BMPR2 variants. Biallelic EIF2AK4 variant carriers had worse survival than BMPR2 variant carriers (p < 0.0001).ConclusionsClinical pictures of PAH patients with BMPR2 and biallelic EIF2AK4 variants in the Chinese population differ from other populations by a younger age at diagnosis and demonstrate female dominance in the whole patient group. High-resolution chest CT can help assist in differentiating PAH with PVOD/PCH. BMPR2 variants and biallelic EIF2AK4 variants are associated with adverse outcomes, but the survival of patients with biallelic EIF2AK4 variants is dismal.

Screening strategies for pulmonary arterial hypertension.

Pulmonary arterial hypertension (PAH) is rare and, if untreated, has a median survival of 2–3 years. Pulmonary arterial hypertension may be idiopathic (IPAH) but is frequently associated with other conditions. Despite increased awareness, therapeutic advances, and improved outcomes, the time from symptom onset to diagnosis remains unchanged. The commonest symptoms of PAH (breathlessness and fatigue) are non-specific and clinical signs are usually subtle, frequently preventing early diagnosis where therapies may be more effective. The failure to improve the time to diagnosis largely reflects an inability to identify patients at increased risk of PAH using current approaches. To date, strategies to improve the time to diagnosis have focused on screening patients with a high prevalence [systemic sclerosis (10%), patients with portal hypertension assessed for liver transplantation (2–6%), carriers of mutations of the gene encoding bone morphogenetic protein receptor type II, and first-degree relatives of patients with heritable PAH]. In systemic sclerosis, screening algorithms have demonstrated that patients can be identified earlier, however, current approaches are resource intensive. Until, recently, it has not been considered possible to screen populations for rare conditions such as IPAH (prevalence 5–15/million/year). However, there is interest in the use of artificial intelligence approaches in medicine and the application of diagnostic algorithms to large healthcare data sets, to identify patients at risk of rare conditions. In this article, we review current approaches and challenges in screening for PAH and explore novel population-based approaches to improve detection.

Bmpr2 Mutant Rats Develop Pulmonary and Cardiac Characteristics of Pulmonary Arterial Hypertension.

Monoallelic mutations in the gene encoding bone morphogenetic protein receptor 2 ( Bmpr2) are the main genetic risk factor for heritable pulmonary arterial hypertension (PAH) with incomplete penetrance. Several Bmpr2 transgenic mice have been reported to develop mild spontaneous PAH. In this study, we examined whether rats with the Bmpr2 mutation were susceptible to developing more severe PAH. The zinc finger nuclease method was used to establish rat lines with mutations in the Bmpr2 gene. These rats were then characterized at the hemodynamic, histological, electrophysiological, and molecular levels. Rats with a monoallelic deletion of 71 bp in exon 1 (Δ 71 rats) showed decreased BMPRII expression and phosphorylated SMAD1/5/9 levels. Δ 71 Rats develop age-dependent spontaneous PAH with a low penetrance (16%-27%), similar to that in humans. Δ 71 Rats were more susceptible to hypoxia-induced pulmonary hypertension than wild-type rats. Δ 71 Rats exhibited progressive pulmonary vascular remodeling associated with a proproliferative phenotype and showed lower pulmonary microvascular density than wild-type rats. Organ bath studies revealed severe alteration of pulmonary artery contraction and relaxation associated with potassium channel subfamily K member 3 (KCNK3) dysfunction. High levels of perivascular fibrillar collagen and pulmonary interleukin-6 overexpression discriminated rats that developed spontaneous PAH and rats that did not develop spontaneous PAH. Finally, detailed assessments of cardiomyocytes demonstrated alterations in morphology, calcium (Ca2+), and cell contractility specific to the right ventricle; these changes could explain the lower cardiac output of Δ 71 rats. Indeed, adult right ventricular cardiomyocytes from Δ 71 rats exhibited a smaller diameter, decreased sensitivity of sarcomeres to Ca2+, decreased [Ca2+] transient amplitude, reduced sarcoplasmic reticulum Ca2+ content, and short action potential duration compared with right ventricular cardiomyocytes from wild-type rats. We characterized the first Bmpr2 mutant rats and showed some of the critical cellular and molecular dysfunctions described in human PAH. We also identified the heart as an unexpected but potential target organ of Bmpr2 mutations. Thus, this new genetic rat model represents a promising tool to study the pathogenesis of PAH.

The role of genetics in pulmonary arterial hypertension.

Group 1 pulmonary hypertension or pulmonary arterial hypertension (PAH) is a rare disease characterized by proliferation and occlusion of small pulmonary arterioles, leading to progressive elevation of pulmonary artery pressure and pulmonary vascular resistance, and right ventricular failure. Historically, it has been associated with a high mortality rate, although, over the last decade, treatment has improved survival. PAH includes idiopathic PAH (IPAH), heritable PAH (HPAH), and PAH associated with certain medical conditions. The aetiology of PAH is heterogeneous, and genetics play an important role in some cases. Mutations in BMPR2, encoding bone morphogenetic protein receptor 2, a member of the transforming growth factor-β superfamily of receptors, have been identified in 70% of cases of HPAH, and in 10-40% of cases of IPAH. Other genetic causes of PAH include mutations in the genes encoding activin receptor-like type 1, endoglin, SMAD9, caveolin 1, and potassium two-pore-domain channel subfamily K member 3. Mutations in the gene encoding T-box 4 have been identified in 10-30% of paediatric PAH patients, but rarely in adults with PAH. PAH in children is much more heterogeneous than in adults, and can be associated with several genetic syndromes, congenital heart disease, pulmonary disease, and vascular disease. In addition to rare mutations as a monogenic cause of HPAH, common variants in the gene encoding cerebellin 2 increase the risk of PAH by approximately two-fold. A PAH panel of genes is available for clinical testing, and should be considered for use in clinical management, especially for patients with a family history of PAH. Copyright © 2016 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Characteristics of Pulmonary Arterial Hypertension in Affected Carriers of a Mutation Located in the Cytoplasmic Tail of Bone Morphogenetic Protein Receptor Type 2

Mutations in BMPR2 encoding bone morphogenetic protein receptor type 2 (BMPRII) is the main genetic risk factor for heritable pulmonary arterial hypertension (PAH). The suspected mechanism is considered to be a defect of BMP signaling. The BMPRII receptor exists in a short isoform without a cytoplasmic tail, which has preserved BMP signaling. This cohort study compared age at PAH diagnosis and severity between patients carrying a BMPR2 mutation affecting the cytoplasmic tail of BMPRII and affected carriers of a mutation upstream of this domain. We identified 171 carriers affected with PAH with a mutated BMPR2. Twenty-three were carriers of a point mutation located on the cytoplasmic tail of BMPRII. This population was characterized by having an older age at diagnosis compared with other BMPR2 mutation carriers (43.2 ± 12.1 years and 35.7 ± 14.6 years, P = .040), a lower pulmonary vascular resistance (13.3 ± 3.5 and 17.4 ± 6.7, P = .023), and a higher proportion of acute vasodilator responders with a long-term response to calcium channel blockers (8.7% and 0%, P = .02). No statistically significant differences were observed in survival. An in vitro assay showed that mutations located in the cytoplasmic tail led to normal activation of the Smad pathway, whereas activation was abolished in the presence of mutations located in the kinase domain. Patients carrying a mutation affecting the cytoplasmic tail of BMPRII were characterized by an older age at diagnosis compared with other BMPR2 mutation carriers, less severe hemodynamic characteristics, and a greater chance of being a long-term responder to calcium channel blockers. Further investigations are needed to better understand the consequences of these BMPR2 mutations in BMPRII signaling pathways and their possible role in pulmonary arterial remodeling.

A Case of Idiopathic Pulmonary Arterial Hypertension with aBMPR2Mutation

본 증례는 국내에서 처음으로 밝혀진 BMPR2 ìœ ì „ìž 돌연변이에 의한 폐동맥 ê³ í˜ˆì••ì¼ 뿐 아니라 ì „ ì„¸ê³„ì ìœ¼ë¡œë„ 처음 발견된 exon 8의 c.1042_1047delGTTATT 돌연변이에 대한 ë³´ê³ ì´ë‹¤. 환자는 NYHA class III ì •ë„ì˜ 운동 시 호흡곤란 및 객혈로 내원한 43세 남자 환자로서 특발성 íë™ë§¥ê³ í˜ˆì••ìœ¼ë¡œ 확진되었다. 중심 단어: íë™ë§¥ê³ í˜ˆì••; BMPR2 돌연변이

Pulmonary arterial hypertension and chronic thromboembolic pulmonary hypertension: pathophysiology

Pulmonary arterial hypertension (PAH) and chronic thromboembolic pulmonary hypertension (CTEPH) are two of the key subgroups of pulmonary hypertension. They are characterised by different risk factors. PAH can be associated with mutations in the gene encoding bone morphogenetic protein receptor type II (BMPR2), HIV infection, congenital heart disease, connective tissue disease (such as systemic sclerosis), and exposure to particular drugs and toxins including fenfluramine derivatives. In contrast, CTEPH can be associated with anti-phospholipid antibodies, splenectomy and the presence of a ventriculo-atrial shunt or an infected pacemaker. The first-line therapies used to treat PAH and CTEPH also differ. While medical therapy tends to be used for patients with PAH, pulmonary endarterectomy is the treatment of choice for patients with CTEPH. However, there are possible common mechanisms behind the two diseases, including endothelial cell dysfunction and distal pulmonary artery remodelling. Further research into these similarities is needed to assist the development of targeted pharmacological therapies for patients with inoperable CTEPH and patients who have persistent pulmonary hypertension after endarterectomy.

Evidence of dysfunction of endothelial progenitors in pulmonary arterial hypertension.

Severe pulmonary arterial hypertension (PAH) is characterized by the formation of plexiform lesions and concentric intimal fibrosis in small pulmonary arteries. The origin of cells contributing to these vascular lesions is uncertain. Endogenous endothelial progenitor cells are potential contributors to this process. To determine whether progenitors are involved in the pathobiology of PAH. We performed immunohistochemistry to determine the expression of progenitor cell markers (CD133 and c-Kit) and the major homing signal pathway stromal cell-derived factor-1 and its chemokine receptor (CXCR4) in lung tissue from patients with idiopathic PAH, familial PAH, and PAH associated with congenital heart disease. Two separate flow cytometric methods were employed to determine peripheral blood circulating numbers of angiogenic progenitors. Late-outgrowth progenitor cells were expanded ex vivo from the peripheral blood of patients with mutations in the gene encoding bone morphogenetic protein receptor type II (BMPRII), and functional assays of migration, proliferation, and angiogenesis were undertaken. measurements and main results: There was a striking up-regulation of progenitor cell markers in remodeled arteries from all patients with PAH, specifically in plexiform lesions. These lesions also displayed increased stromal cell-derived factor-1 expression. Circulating angiogenic progenitor numbers in patients with PAH were increased compared with control subjects and functional studies of late-outgrowth progenitor cells from patients with PAH with BMPRII mutations revealed a hyperproliferative phenotype with impaired ability to form vascular networks. These findings provide evidence of the involvement of progenitor cells in the vascular remodeling associated with PAH. Dysfunction of circulating progenitors in PAH may contribute to this process.

Mutations in the Gene Encoding Bone Morphogenetic Protein Receptor 2 in Patients With Idiopathic Pulmonary Arterial Hypertension

Pulmonary arterial hypertension (PAH) is a rare disease that can have a familial component. It has been shown that more than 50% of cases of familial PAH are associated with mutations in the gene encoding bone morphogenetic protein receptor 2 (BMPR2), which acts as a receptor for members of the transforming growth factor beta superfamily. Some studies in patients with idiopathic PAH have also shown varying percentages of mutations in this gene. The aim of this study was to determine the frequency of these mutations in a group of patients with idiopathic PAH. The study population included patients with idiopathic PAH who were seen during 2006 in our unit specialized in this entity. Patients were excluded if they had relatives who had been diagnosed with PAH or who had symptoms that led to suspicion of the disease. Diagnosis was obtained according to the protocol used in our unit. A hemodynamic study was carried out in all cases and patients were included if they had a mean pulmonary arterial pressure of greater than 25 mm Hg. DNA was extracted from peripheral leukocytes and amplified by polymerase chain reaction. Seventeen primer pairs were used for the 13 exons that make up the gene. Using the single strand conformational polymorphism (SSCP) technique we detected anomalous DNA fragments for subsequent sequencing. The study included 8 patients (4 women). In 5 patients, no abnormalities were observed, whereas in the remaining 3, anomalous electrophoresis patterns were obtained in the SSCP and sequencing revealed mutations. In 1 case, 2 different electrophoresis patterns were observed by SSCP, but it was only possible to sequence 1 of them due to the low concentration of DNA obtained. The presence of mutations in the gene encoding BMPR2 is not infrequent in patients with idiopathic PAH, suggesting that this family of growth factors may be important in the pathogenesis of the disease and could have therapeutic implications.

The Effect of Statins in Colorectal Cancer Is Mediated Through the Bone Morphogenetic Protein Pathway

Epidemiological evidence suggests that statins prevent colorectal cancer (CRC), but the biological mechanism remains obscure. Statins induce bone morphogenetic protein (BMP) expression in bone cells. We have previously shown that BMPs act as tumor suppressors in CRC. We hypothesized that the action of statins in CRC involves the induction of BMPs. We investigated the effects of statins on CRC cell lines using immunoblotting, measurements of apoptosis and cell proliferation, and luciferase reporter assays. The effect of statins was confirmed in a xenograft mouse model. CRC cell lines show widely differing sensitivities to statin treatment. Sensitive cell lines show induction of BMP2 protein levels and a BMP2 reporter construct, activation of the BMP pathway, and induction of the BMP target gene ID-2, whereas resistant cell lines do not. The addition of the specific inhibitor of BMPs, noggin, completely prevents lovastatin-induced apoptosis in sensitive cells. Sensitive cell lines express the central BMP pathway element SMAD4, whereas the resistant cell lines do not. Targeted knockout of SMAD4 leads to the loss of statin sensitivity and reconstitution with SMAD4, to the restoration of statin sensitivity. In a xenograft mouse model, tumors from sensitive and insensitive cell lines were treated with oral simvastatin. Significant inhibition of tumor growth using sensitive cells but increased tumor growth when using insensitive cells was observed. Statins induce apoptosis in CRC cells through induction of BMP2. Statin therapy may only be effective in SMAD4-expressing CRCs and may have adverse effects in SMAD4-negative tumors.

Inherited Polyposis Syndromes: Molecular Mechanisms, Clinicopathology, and Genetic Testing

The inherited polyposis syndromes are a group of conditions in which multiple gastrointestinal polyps occur in the lumen of the gastrointestinal tract, most exhibit an increased risk of colon cancer. Benign and malignant extraintestinal tumors might also be observed. Recent elucidation of the underlying gene mutations has contributed to our understanding of the cell biology and molecular mechanisms associated with gastrointestinal tumorigenesis. Developments have also allowed genetic testing to become an integral component in accurate diagnosis, categorization, and management of inherited polyposis syndromes. In this review, we will focus on familial adenomatous polyposis, mutY human homologue-associated polyposis, Peutz-Jeghers syndrome, juvenile polyposis, and Cowden syndrome. It is essential that both physician and patient understand the benefits and limitations of genetic testing before submission of samples to the laboratory. There are many issues accompanying molecular diagnosis of cancer syndromes, and genetic counseling is an essential prelude to genetic testing.

BMPR2 mutations in pulmonary arterial hypertension with congenital heart disease.

The aim of the present study was to determine if patients with both pulmonary arterial hypertension (PAH), due to pulmonary vascular obstructive disease, and congenital heart defects (CHD), have mutations in the gene encoding bone morphogenetic protein receptor (BMPR)-2. The BMPR2 gene was screened in two cohorts: 40 adults and 66 children with PAH/CHD. CHDs were patent ductus arteriosus, atrial and ventricular septal defects, partial anomalous pulmonary venous return, transposition of the great arteries, atrioventicular canal, and rare lesions with systemic-to-pulmonary shunts. Six novel missense BMPR2 mutations were found in three out of four adults with complete type C atrioventricular canals and in three children. One child had an atrial septal defect and patent ductus arteriosus; one had an atrial septal defect, patent ductus arteriosus and partial anomalous pulmonary venous return; and one had an aortopulmonary window and a ventricular septal defect. Bone morphogenetic protein receptor 2 mutations were found in 6% of a mixed cohort of adults and children with pulmonary arterial hypertension/congenital heart defects. The current findings compliment recent reports in mouse models implicating members of the bone morphogenetic protein/transforming growth factor-beta pathway inducing cardiac anomalies analogous to human atrioventricular canals, septal defects and conotruncal congenital heart defects. The small number of patients studied and the ascertainment bias inherent in selecting for pulmonary arterial hypertension require further investigation.

Mutation in the gene for bone morphogenetic protein receptor II as a cause of primary pulmonary hypertension in a large kindred.

Most patients with primary pulmonary hypertension are thought to have sporadic, not inherited, disease. Because clinical disease develops in only 10 to 20 percent of persons carrying the gene for familial primary pulmonary hypertension, we hypothesized that many patients with apparently sporadic primary pulmonary hypertension may actually have familial primary pulmonary hypertension. In a study conducted over 20 years, we developed a registry of 67 families affected by familial primary pulmonary hypertension. Through patient referrals, extensive family histories, and correlation of family pedigrees, we discovered shared ancestry among five subfamilies. We established the diagnosis of primary pulmonary hypertension by direct evaluation of patients and review of autopsy material and medical records. We assessed some family members for mutations in the gene encoding bone morphogenetic protein receptor II (BMPR2), which has recently been found to cause familial primary pulmonary hypertension. We linked five separately identified subfamilies that included 394 known members spanning seven generations, which were traced back to a founding couple in the mid-1800s. Familial primary pulmonary hypertension has been diagnosed in 18 family members, 12 of whom were first thought to have sporadic disease. The conditions of 7 of the 18 were initially misdiagnosed as other cardiopulmonary diseases. Six members affected with familial primary pulmonary hypertension and 6 of 10 at risk for carriage have been undergone genotype analysis, and they have the same mutation in BMPR2, a transversion of thymine to guanine at position 354 in exon 3. Many cases of apparently sporadic primary pulmonary hypertension may be familial. Failure to detect familial primary pulmonary hypertension results from incomplete expression within families, skipped generations, and incomplete family pedigrees. The recent discovery of mutations in BMPR2 should make it possible to identify those with susceptibility to disease.

Germline mutations of the gene encoding bone morphogenetic protein receptor 1A in juvenile polyposis.

Juvenile polyposis (JP; OMIM 174900) is an autosomal dominant gastrointestinal hamartomatous polyposis syndrome in which patients are at risk for developing gastrointestinal cancers. Previous studies have demonstrated a locus for JP mapping to 18q21.1 (ref. 3) and germline mutations in the homolog of the gene for mothers against decapentaplegic, Drosophila, (MADH4, also known as SMAD4) in several JP families. However, mutations in MADH4 are only present in a subset of JP cases, and although mutations in the gene for phosphatase and tensin homolog (PTEN) have been described in a few families, undefined genetic heterogeneity remains. Using a genome-wide screen in four JP kindreds without germline mutations in MADH4 or PTEN, we identified linkage with markers from chromosome 10q22-23 (maximum lod score of 4.74, straight theta=0.00). We found no recombinants using markers developed from the vicinity of the gene for bone morphogenetic protein receptor 1A (BMPR1A), a serine-threonine kinase type I receptor involved in bone morphogenetic protein (BMP) signaling. Genomic sequencing of BMPR1A in each of these JP kindreds disclosed germline nonsense mutations in all affected kindred members but not in normal control individuals. These findings indicate involvement of an additional gene in the transforming growth factor-beta (TGF-beta) superfamily in the genesis of JP, and document an unanticipated function for BMP in colonic epithelial growth control.