• E-mail
• Print
• Comment
• Font Size
• Digg
• del.icio.us
• Discuss article

Clinical Outcomes of Pulmonary Arterial Hypertension in Carriers of BMPR2 Mutation

Posted on: Tuesday, 17 June 2008, 03:00 CDT

By Sztrymf, Benjamin Coulet, Florence; Girerd, Barbara; Yaici, Azzedine; Jais, Xavier; Sitbon, Olivier; Montani, David; Souza, Rogerio; Simonneau, Gerald; Soubrier, Florent; Humbert, Marc

Rationale: Germline mutations in the gene encoding for bone morphogenetic protein receptor 2 (BMPR2) are a cause of pulmonary arterial hypertension (PAH). Objectives:We conducted a study to determine the influence, if any, of a BMPR2 mutation on clinical outcome.

Methods: The French Network of Pulmonary Hypertension obtained data for 223 consecutive patients displaying idiopathic or familial PAH in whom point mutation and large size rearrangements of BMPR2 were screened for. Clinical, functional, and hemodynamic characteristics, as well as outcomes, were compared in BMPR2 mutation carriers and noncarriers.

Measurements and Main Results: Sixty-eight BMPR2 mutation carriers (28 familial and 40 idiopathic PAH) were compared with 155 noncarriers (all displaying idiopathic PAH). As compared with noncarriers, BMPR2 mutation carriers were younger at diagnosis of PAH (36.5 +- 14.5 vs. 46.0 +- 16.1 yr, P < 0.0001), had higher mean Pulmonary artery pressure (64 +- 13 vs. 56+- 13mmHg, P < 0.0001), lower cardiac index (2.13 +- 0.68 vs. 2.50 +- 0.73 L/min/m^sup 2^, P = 0.0005), higher pulmonary vascular resistance (17.4 +- 6.1 vs. 12.7 +- 6.6 mm Hg/L/min/m^sup 2^, P < 0.0001), lower mixed venous oxygen saturation (59 +- 9% vs. 63 +- 9%, P = 0.02), shorter time to death or lung transplantation (P = 0.044), and younger age at death (P = 0.002), but similar overall survival (P = 0.51).

Conclusions: BMPR2 mutation carriers with PAH present approximately 10 years earlier than noncarriers, with a more severe hemodynamic compromise at diagnosis.

Keywords: bone morphogenetic protein receptor 2; genetics; hemodynamics; pulmonary arterial hypertension; survival

Pulmonary arterial hypertension (PAH) is a severe disease affecting small pulmonary arteries, with a progressive remodeling leading to elevated pulmonary vascular resistance and right ventricular failure (1). PAH may occur in different clinical contexts, depending on associated clinical conditions (1, 2). Idiopathic PAHcorresponds to sporadic disease, without any familial history of PAH or known triggering factor (2). When PAH occurs in a familial context (2-5), germline mutations in the bone morphogenetic protein receptor 2 (BMPR2) gene are detected in at least 70% of cases (6-10). BMPR2 mutations can also be detected in 11 to 40% of apparently sporadic cases (10-15). The distinction between idiopathic and familial BMPR2 mutation carriers may in fact be artificial, as these subjects have an inherited condition and may all correspond to a potential familial disease. Recent expert discussion pleads in favor of the term "heritable" PAHto describe these genetic forms of the disease. In any case, BMPR2 mutation represents the major genetic predisposing factor for PAH (6-17).

The BMPR2 gene encodes a type 2 receptor for bone morphogenetic proteins, which belong to the transforming growth factor-beta superfamily (16). Among several biological functions, bone morphogenetic proteins are involved in the control of vascular cell proliferation (16). Heterozygous inactivating mutations of BMPR2 are responsible for functional haploinsufficiency of the bone morphogenetic proteins' transduction pathway, and lead to proliferation of smooth muscle cells within pulmonary arteries (17). However, the penetrance of BMPR2 mutations is low (around 20%), and neither the factors involved in the initiation of the disease in affected subjects nor the precise molecular mechanisms underlying the responsibility of BMPR2 haploinsufficiency in the disease are identified (5, 16, 17). Previous reports have suggested that the clinical and hemodynamic presentation of familial PAH was not different from idiopathic PAH, with similar pathologic lesions as well as molecular and cellular abnormalities described in both subtypes (16, 18). However, a significant proportion of so-called idiopathic cases were in fact associated with BMPR2 mutations and this might have given a biased comparison (11). Recent findings have indicated that BMPR2 mutation carriers with familial or idiopathic PAH were less likely to display vasoreactivity than noncarriers, raising the possibility that monoallelic BMPR2 mutation identifies patients who may respond poorly to long-term vasodilator therapy (19).

We hypothesized that a mutated BMPR2 status is associated with distinct disease phenotypes. To test this hypothesis, the French Network of Pulmonary Hypertension obtained data on consecutive patients displaying idiopathic or familial PAH in whom point mutation and large size rearrangements of BMPR2 were screened for. Clinical, functional, and hemodynamic characteristics, as well as outcomes, were compared in BMPR2 mutation carriers and noncarriers.

METHODS

Patients

Patients were seen within the French Network of Pulmonary Hypertension between January 1, 2004, and June 1, 2007. In accordance with the guidelines of the American College of Chest Physicians (20), patients with idiopathic and familial PAH tested for BMPR2 mutations underwent genetic counseling and signed written, informed consent. Two hundred and thirty-three consecutive patients (195 idiopathic and 38 familial PAH) were tested for BMPR2 point mutation and large size rearrangements. This corresponded to 68 BMPR2 mutation carriers (40 idiopathic and 28 familial), 155 idiopathic PAH noncarriers, and 10 patients with familial PAH with no evidence of BMPR2 mutation. Patients with familial PAH with no evidence of BMPR2 mutation were excluded from the analysis to decrease the risk of misclassification in the BMPR2 mutation noncarrier group (Figure 1).

A diagnosis of PAH was established by means of right heart catheterization and acute vasodilator challenge was performed through inhalation of nitric oxide or intravenous injection of prostacyclin, according to previously described methods (1, 21, 22). Idiopathic PAH was recognized after ruling out all associated conditions of pulmonary hypertension, summarized in the revised classification, and by determining no existence of additional pulmonary hypertension cases in the family of the patient (2). Familial PAH was recognized if there was more than one confirmed case in the family (2).

All clinical characteristics at PAH diagnosis and follow-up were stored in the Registry of the French Network of Pulmonary Hypertension. This registry was set up in agreement with French bioethics laws (French Commission Nationale de l'Informatique et des Libertes), and all patients gave their informed consent (23). The six-minute-walk distance as well as the percentage of reference values were studied (23, 24). All patients were treated according to international guidelines, which recommend a similar management in familial and idiopathic PAH (25, 26).

Molecular Methods

Screening of point mutations in the coding regions and intronic junctions of BMPR2. Amplification of all coding exons and intronic junctions of the BMPR2 gene was performed on genomicDNAfrom each individual using 16 fragments, with primers described in Table 1. Genetic variation of BMPR2 sequence was detected by denaturing high- performance liquid chromatography (dHPLC) using aWAVENucleic Acid Fragment Analysis System (Transgenomic, Elancourt, France). The temperature used for successful resolution of heteroduplex molecules was determined by the dHPLC melting algorithm and a control polymerase chain reaction (PCR) product (with a known mutation). Samples with an altered dHPLC profile were sequenced using the BigDye Terminator v1.1 cycle sequencing kit (Applied Biosystems, Foster city, CA) on an ABI 3730 DNA sequencer (Applied Biosystems). The resulting sequences were compared with the reference sequence of BMPR2 gene (accession no. NM_001204) with the ABI SeqScape software, version 2.5 (Applied Biosystems).

Screening of BMPR2 large size rearrangements. The BMPR2 gene was screened for large size rearrangements either using the SALSA multiplex ligation-dependent probe amplification (MLPA) P093 HHT probe mix kit (MRC-Holland BV, Amsterdam, The Netherlands) according to the manufacturer's instructions or by quantitative multiplex PCR of fluorescent short fragments (QMPSF) (27). In the latter case, BMPR2 exons were amplified (size of fragments ranging from 132 to 308 bp) in three multiplex PCRs and the forward primer of each pair was 5'-labeled with the 6-Fam fluorochrome. Fragment analysis of multiplex PCR (from MLPA or QMPSF) was performed on an ABI 3730 DNA analyzer and results were analyzed using GeneMapper software, version 4.0 (Applied Biosystems). Two DNA samples from unaffected individuals were used as controls in each experiment. Electrophoregrams were superimposed on those generated with a controlDNAby adjusting to the same levels the peaks obtained for the control amplicons.

Statistical Analysis

We compared demographic and clinical features between BMPR2 mutation carriers and noncarriers with the use of x^sup 2^, Fisher's exact test, Mann-Whitney test, or t test, as appropriate. Both the time to death (patients undergoing lung transplantation were considered as censored at the date of transplantation) and the time to death or lung transplantation (patients undergoing lung transplantation were considered as an event at the date of transplantation) were described using Kaplan-Meier curves, and compared with the use of the log-rank test. A P value of less than 0.05 was considered to indicate statistical significance. RESULTS

Clinical and Functional Characteristics

A BMPR2 mutation was identified in 40 of 195 idiopathic PAH (20.5%) and 28 of 38 familial cases (73.7%). We thus compared 68 idiopathic and familial BMPR2 mutation carriers with 155 idiopathic PAH noncarriers.

Age at diagnosis of PAH was significantly younger in BMPR2 mutation carriers, as compared with noncarriers (34.5 +- 14.5 vs. 46.0 +- 16.1 yr, P < 0.0001; Table 2). No other clinical differences were found between the two subgroups at diagnosis, including a similar female predisposition to PAH, regardless of BMPR2 status (Table 3). Six-minute-walk distance at diagnosis was 351 +- 106 m in BMPR2 mutation carriers versus 328 +- 120 m in noncarriers (P = 0.21). Because patients with BMPR2 mutations were younger, we also expressed the six-minute-walk distance as a percentage of reference values (55 +- 14 in carriers vs. 60 +- 21% of predicted values in noncarriers, P = 0.17).

Hemodynamics

As compared with noncarriers, BMPR2 mutation carriers were characterized by a more severe hemodynamic compromise at diagnosis, with a significantly higher mean pulmonary artery pressure (Ppa) (64 +- 13 vs. 56 +- 13 mm Hg, P < 0.0001), a lower cardiac index (2.13 +- 0.68 vs. 2.50 +- 0.73 L/min/m^sup 2^, P = 0.0005), a higher pulmonary vascular resistance (17.4 +- 6.1 vs. 12.7 +- 6.6 mm Hg/L/ min/m^sup 2^, P < 0.0001), and a lower mixed venous oxygen saturation (53 +- 9 vs 59 +- 9%, P = 0.02). Mutation carriers were less likely to exhibit a significant response to acute vasodilatory test during right heart catheterization (defined by a fall in Ppa of least 10mmHg, reaching an absolute value of Ppa under 40 mm Hg, associated with no change or an increase in cardiac index) (Table 3) (19, 22, 25, 28).

Medical Management

Due to their more severe hemodynamic baseline presentation, BMPR2 mutation carriers were more likely to receive intravenous prostacyclin as first-line therapy (58 vs. 27%, P = 0.015). In addition, BMPR2 mutation carriers were more likely to undergo lung transplantation when compared with noncarriers (11/68 carriers vs. 8/ 155 noncarriers, P = 0.007).

Survival

Fifty-five of the 223 patients died (18 BMPR2 mutation carriers and 37 noncarriers), with a similar overall survival in both groups (Figure 2A). BMPR2 mutation carriers were more likely to undergo lung transplantation, with a significantly shorter time to death or lung transplantation when compared with noncarriers (log-rank test, P = 0.044; Figure 2B). In addition, BMPR2 mutation carriers developed the disease and subsequently died younger than noncarriers (age at death was 34.4 +- 15.1 vs. 50.5 +- 17.5 yr, P = 0.003) (Figure 3).

BMPR2 Mutations

Germline BMPR2 mutations were located throughout the BMPR2 gene, affecting regions of the gene encoding for the four main parts of the protein (ligand binding, transmembrane region, kinase domain, and cytoplasmic tail). Five long deletions have been identified in the present series, corresponding to two exon 10 deletions, one large deletion from exons 1 to 4, one deletion of exons 11 to 13, and a deletion of the whole allele (Table 4).

DISCUSSION

We have studied a group of 223 patients with familial and idiopathic PAH with or without germline BMPR2 mutations and treated according to the best standard of care in a national pulmonary hypertension network. Our results indicate that there is a significantly increased severity of hemodynamic status in BMPR2 mutation carriers at diagnosis when compared with noncarriers, as demonstrated by higher Ppa, lower cardiac index, higher total pulmonary resistance, and lower mixed oxygen saturation. Although there was no difference in overall survival after diagnosis, BMPR2 mutation carriers had a significantly shorter time to death or lung transplantation, indicating that they were more likely to undergo lung transplantation. Because lung transplantation is the ultimate alternative for severe PAH cases who cannot be managed medically (25), time to death or transplantation is an indicator of disease severity in this patient population (29). In addition, BMPR2 mutation carriers developed the disease earlier with fatal events occurring at a younger age. Therefore, the overall findings plead in favor of a more severe disease state in patients with BMPR2 mutation. In recent registries, including the French registry (23), no difference between familial and idiopathic PAH could be evidenced in terms of severity, presumably because of the substantial proportion of BMPR2 mutation carriers in each group, which in fact biased the comparison. The present comprehensive analysis of well- defined BMPR2 mutation carriers and noncarriers allows avoiding such a bias.

The observation that subjects with BMPR2 mutation develop the disease earlier and with a more severe hemodynamic compromise illustrates the constitutive susceptibility conferred by the mutation on the course of the disease. Although the penetrance of BMPR2 mutation is low, in agreement with data from mice with heterozygous inactivation of BMPR2, which only shows a susceptibility to inflammatory stress or excess serotonin (30, 31), BMPR2 haploinsufficiency determines a pulmonary vascular status that leads to PAH in an accelerated fashion. The younger age of onset is also observed for other diseases where an inherited genetic factor confers a strong predisposition, as in hereditary forms of breast and colon cancer. In these cases, a heterozygous germline mutation in a DNA repair gene or tumor suppressor gene favors a second genetic event, or second hit, which in turn leads to a series of somatic mutations in specific cells and to the development of cancer (32). In the case of BMPR2 mutation, the gene is involved in proliferation of pulmonary artery vascular smooth muscle cells under the control of bone morphogenetic proteins. Indeed, a reduced apoptotic response to bone morphogenetic proteins was shown in pulmonary artery vascular smooth muscle cells from pulmonary hypertensive patients with a BMPR2 mutation, as compared with control cells, suggesting a change in phenotype secondary to genetic events (33, 34). Somatic genetic events were investigated in smooth muscle cells from affected pulmonary arteries, such as DNA microsatellite instability, a hallmark of genome instability, or loss of heterozygosity attesting chromosomal deletion, but negative results do not plead in favor of the hypothesis of a second genetic somatic event (35). Although other kinds of somatic genetic or epigenetic events cannot be eliminated, their nature remains elusive.

Any familial disease may lead to an earlier diagnosis in subsequent similar cases. However, a majority of BMPR2 mutant carriers from the present study displayed idiopathic PAH (40 of 68, 59%). In addition, 5 of 28 familial cases of BMPR2 mutant carriers were the first identified case in these families. Therefore, only 23 BMPR2 mutant carriers (34%) had a familial history of PAH at diagnosis. Thus, heightened suspicion of PAH was present in a minority of BMPR2 mutant carriers. To further analyze this population, we have compared delay between onset of symptoms and diagnosis in patients with or without familial history of PAH. As expected, patients with a history of PAH had a shorter delay between onset of symptoms and diagnosis (1.5 +- 2.3 vs. 0.6 +- 0.6 yr, P = 0.036). This could not explain the differences in disease presentation, such as the more than 10-year age difference at diagnosis and death between BMPR2 mutation carriers and noncarriers. The later onset in noncarriers could imply that, compared with patients with a germline BMPR2 haploinsufficiency, additional events are required for the disease to develop, resulting in a significant older age of onset. The nature of these events is unknown, and they are probably partially similar to those involved in BMPR2 mutation carriers. For example, a down-regulation of the bone morphogenetic protein pathway is observed in both types of smooth muscle cells, either from BMPR2 mutation carriers or noncarriers. In this latter case, the down-regulation origin is unknown (36). The worse hemodynamic parameters at diagnosis in BMPR2 mutation carriers might reflect an accelerated process of the disease, but this is not confirmed by the overall survival. Nevertheless, time to death or lung transplantation was shorter in BMPR2 mutation carriers as compared with noncarriers, further suggesting that BMPR2 mutation confers a more severe phenotype.

The disequilibrium in the female/male ratio was previously reported for familial and idiopathic PAH (5, 23, 37, 38) and many hypotheses have been raised to explain it, including a disadvantage of male embryos carrying a BMPR2 mutation (5). Interestingly, the female/male ratio was identical in BMPR2 mutation carriers and noncarriers, suggesting that this disequilibrium does not result from a meiotic drive or embryonic lethality but more likely from specific sex-dependent factors acting later in life and favoring the occurrence of the disease in females.

We have excluded from the analysis the 10 patients with familial PAH who did not carry BMPR2 mutations. It is possible, however, that these patients carry mutations in some unexplored parts of the BMPR2 gene. As mentioned in METHODS, we have performed amplification of all coding exons and intronic junctions of the BMPR2 gene and may thus miss alterations in other intronic regions or other mechanisms, such as epigenetic alterations of this gene that have not been recognized at this time. This possibility has been partly evaluated by Aldred and colleagues who analyzed part of the 5'-untranslated region and promoter of the gene in familial PAH (39). DNA upstream of the coding region was analyzed by direct sequencing in 16 families. In one family, a mutation predicted to form a cryptic translational start site was identified. This mutant transcript contains a premature stop codon (39). These results further emphasize the possibility that current techniques could miss BMPR2 mutations in some patients. In conclusion, BMPR2 mutation carriers with PAH present approximately 10 years earlier than noncarriers with a more severe hemodynamic compromise at diagnosis. A better understanding of the mechanisms by which BMPR2 mutations define a subclass of patients with more severe disease is critical for improving our knowledge of PAH.

Conflict of Interest Statement: None of the authors has a financial relationship with a commercial entity that has an interest in the subject of this manuscript.

Acknowledgment: The authors thank Dr. Gregory Raux (Service de Genetique CHU Charles Nicolle ROUEN) for the design of QMPSF primers and Ms. Rebecca Honan for reading the manuscript.

AT A GLANCE COMMENTARY

Scientific Knowledge on the Subject

Germline mutations in the gene encoding for bone morphogenetic protein receptor 2 (BMPR2) are a cause of pulmonary arterial hypertension. The influence, if any, of aBMPR2 mutation on clinical outcomes is currently unknown.

What This Study Adds to the Field

BMPR2 mutation carriers with pulmonary arterial hypertension present approximately 10 years earlier than noncarriers with a more severe hemodynamic compromise at diagnosis.

References

1. Runo JR, Loyd JE. Primary pulmonary hypertension. Lancet 2003;361: 1533-1544.

2. Simonneau G, Galie N, Rubin LJ, Langleben D, SeegerW, Domenighetti G, Gibbs S, Lebrec D, Speich R, BeghettiM, et al. Clinical classification of pulmonary arterial hypertension. J AmColl Cardiol 2004;43:5S-12S.

3. Dresdale DT, Mitchom RJ, Schultz M. Recent studies in primary pulmonary hypertension, including pharmacodynamic observations on pulmonary vascular resistance. BullNYAcad Med 1954;30:195-207.

4. Loyd JE, Primm RK, Newman JH. Familial primary pulmonary hypertension: clinical patterns. Am Rev Respir Dis 1984;129:194- 197.

5. Loyd JE, Butler MG, Foroud TM, Conneally PM, Philips JA 3rd, Newman JH. Genetic anticipation and abnormal gender ratio at birth in familial primary pulmonary hypertension. Am J Respir Crit Care Med 1995;152:93-97.

6. Lane KB, Machado RD, Pauciulo MW, Thomson JR, Phillips JA 3rd, Loyd JE, Nichols WC, Trembath RC. Heterozygous germline mutations in a TGFb receptor, BMPR2, are the cause of familial primary pulmonary hypertension. Nat Genet 2000;26:81-84.

7. Deng Z, Morse JH, Slager SL, Cuervo N, Moore KJ, Venetos G, Kalachikov S, Cayanis E, Fischer SG, Barst RJ, et al. Familial primary pulmonary hypertension (gene PPH1) is caused by mutations in the bone morphogenetic protein receptor-II gene. Am J Hum Genet 2000; 67:737-744.

8. Newman JH, Wheeler L, Lane KB, Loyd E, Gaddipati R, Phillips JA 3rd, Loyd JE. Mutation in the gene for bone morphogenetic protein receptor II as a cause of primary pulmonary hypertension in a large kindred. N Engl J Med 2001;345:319-324.

9. Cogan JD, Pauciulo MW, Batchman AP, Prince MA, Robbins IM, Hedges LK, Stanton KC, Wheeler LA, Phillips JA 3rd, Loyd JE, et al. High frequency of BMPR2 exonic deletions/duplications in familial pulmonary arterial hypertension. Am J Respir Crit Care Med 2006; 174:590-598.

10. Aldred MA, Vijayakrishnan J, James V, Soubrier F, Gomez- Sanchez MA, Martensson G, GalieN,Manes A, Corris P, SimonneauG, et al. BMPR2 gene rearrangements account for a significant proportion ofmutations in familial and idiopathic pulmonary arterial hypertension. Hum Mutat 2006;27:212-213.

11. Thomson JR, Machado RD, Pauciulo MW, Morgan NV, Humbert M, Elliott GC, Ward K, Yacoub M, Mikhail G, Rogers P, et al. Sporadic primary pulmonary hypertension is associated with germline mutations of the gene encoding BMPR-II, a receptor member of the TGFb family. J Med Genet 2000;37:741-745.

12. Humbert M, Deng Z, Simonneau G, Barst RJ, Sitbon O, Wolf M, Cuervo N, Moore KJ, Hodge SE, Knowles JA, et al. BMPR2 germline mutations in pulmonary hypertension associated with fenfluramine derivatives. Eur Respir J 2002;20:518-523.

13. Koehler R, Grunig E, Pauciulo MW, Hoeper MM, Olschewski H, Wilkens H, Halank M, Winkler J, Ewert R, Bremer H, et al. Low frequency of BMPR2 mutations in a German cohort of patients with sporadic idiopathic pulmonary arterial hypertension. J Med Genet 2004;41:e127.

14. Morisaki H, Nakanishi N, Kyotani S, Takashima A, Tomoike H, Morisaki T. BMPR2 mutations found in Japanese patients with familial and sporadic primary pulmonary hypertension. Hum Mutat 2004;23:632.

15. Machado RD, Aldred MA, James V, Harrison RE, Patel B, Schwalbe EC, Gruenig E, Janssen B, Koehler R, Seeger W, et al. Mutations of the TGF-b type II receptor BMPR2 in pulmonary arterial hypertension. Hum Mutat 2006;27:121-132.

16. Sztrymf B, Yaici A, Girerd B, Humbert M. Genes and pulmonary hypertension. Respiration 2007;74:123-132.

17. Machado RD, Pauciulo MW, Thomson JR, Lane KB, Morgan NV, Wheeler L, Phillips JA 3rd, Newman J, Williams D, Galie N, et al. BMPR2 haploinsufficiency as the inherited molecular mechanism for primary pulmonary hypertension. Am J Hum Genet 2001;68:92-102.

18. Humbert M, Morrell NW, Archer SL, Stenmark KR, MacLean MR, Lang IM, Christman BW, Weir EK, Eickelberg O, Voelkel NF, et al. Cellular and molecular pathobiology of pulmonary arterial hypertension. J Am Coll Cardiol 2004;43:13S-24S.

19. Elliott CG, Glissmeyer EW, Havlena GT, Carlquist J, McKinney JT, Rich S, McGoon MD, Scholand MB, Kim M, Jensen RL, et al. Relationship of BMPR2 mutations to vasoreactivity in pulmonary arterial hypertension. Circulation 2006;113:2509-2515.

20. McGoon M, Gutterman D, Steen V, Barst R, McCrory DC, Fortin TA, Loyd JE. Screening, early detection and diagnosis of pulmonary arterial hypertension: ACCP evidence based clinical practice guidelines. Chest 2004;126:14S-34S.

21. Sitbon O, Humbert M, Jagot JL, Taravella O, Fartoukh M, Parent F, Herve P, Simonneau G. Inhaled nitric oxide as a screening agent for safely identifying responders to oral calcium-channel blockers in primary pulmonary hypertension. Eur Respir J 1998;12:265- 270.

22. Sitbon O, Humbert M, Jais X, loos V, Hamid AM, Provencher S, Garcia G, Parent F, Herve P, Simonneau G. Long-term response to calcium channel blockers in idiopathic pulmonary arterial hypertension. Circulation 2005;111:3105-3111.

23. Humbert M, Sitbon O, Chaouat A, Bertocchi M, Habib G, Gressin V, Yaici A, Weitzenblum E, Cordier JF, Chabot F, et al. Pulmonary arterial hypertension in France: results from a national registry. Am J Respir Crit Care Med 2006;173:1023-1030.

24. Enright PL, Sherrill DL. Reference equations for the six- minute walk in healthy adults. Am J Respir Crit Care Med 1998;158:1384-1387.

25. Humbert M, Sitbon O, Simonneau G. Treatment of pulmonary arterial hypertension. N Engl J Med 2004;351:1425-1436.

26. Galie N, Torbicki A, Barst R, Dartevelle P, Haworth S, Higenbottam T, Olschewski H, Peacock A, Pietra G, Rubin LJ, et al. Guidelines on diagnosis and treatment of pulmonary arterial hypertension. The Task Force on Diagnosis and Treatment of Pulmonary Arterial Hypertension of the European Society of Cardiology. Eur Heart J 2004;25:2243-2278.

27. Tournier I, Paillerets BB, Sobol H, Stoppa-Lyonnet D, Lidereau R, Barrois M, Mazoyer S, Coulet F, Hardouin A, Chompret A, et al. Significant contribution of germline BRCA2 rearrangements in male breast cancer families. Cancer Res 2004;64:8143-8147.

28. Badesch DB, Abman SH, Ahearn GS, Barst RJ,McCrory DC, Simonneau G, McLaughlin VV. Medical therapy for pulmonary arterial hypertension: ACCP evidence based practice guidelines. Chest 2004;126:35S-62S.

29. Montani D, Souza R, Binkert C, Fischli W, Simonneau G, Clozel M, Humbert M. Endothelin-1/endothelin-3 ratio: a potential prognostic factor of pulmonary arterial hypertension. Chest 2007;131:101-108.

30. Yuan JX, Rubin LJ. Pathogenesis of pulmonary arterial hypertension: the need for multiple hits. Circulation 2005;111:534- 538.

31. Long L, MacLean MR, Jeffery TK, Morecroft I, Yang X, Rudarakanchana N, Southwood M, James V, Trembath RC, Morrell NW. Serotonin increases susceptibility to pulmonary hypertension in BMPR2-deficient mice. Circ Res 2006;98:818-827.

32. Knudson AG. Cancer genetics. Am J Med Genet 2002;111:96-102.

33. Zhang S, Fantozzi I, Tigno DD, Yi ES, Platoshyn O, Thistlethwaite PA, Kriett JM, Yung G, Rubin LJ, Yuan JX. Bone morphogenetic proteins induce apoptosis in human pulmonary vascular smooth muscle cells. Am J Physiol Lung Cell Mol Physiol 2003;285:L740-L754.

34. Lagna G, Nguyen PH, Ni W, Hata A. BMP-dependent activation of caspase-9 and caspase-9 mediates apoptosis in pulmonary artery smooth muscle cells. Am J Physiol Lung Cell Mol Physiol 2006;291: L1059-L1067.

35. Machado RD, James V, Southwood M, Harrison RE, Atkinson C, Stewart S, Morrell NW, Trembath RC, Aldred MA. Investigation of second genetic hits at the BMPR2 locus as a modulator of disease progression in familial pulmonary arterial hypertension. Circulation 2005;111:607-613.

36. Atkinson C, Stewart S, Upton PD, Machado R, Thomson JR, Trembath RC, Morrell NW. Primary pulmonary hypertension is associated with reduced pulmonary vascular expression of type II bone morphogenetic protein receptor. Circulation 2002;105:1672- 1678.

37. Rich S, Dantzker DR, Ayres SM, Bergofsky EH, Brundage BH, Detre KM, Fishman AP, Goldring RM, Groves BM, Koerner SK, et al. Primary pulmonary hypertension: a national prospective study. Ann Intern Med 1987;107:216-223.

38. D'Alonzo GE, Barst RJ, Ayres SM, Bergofsky EH, Brundage BH, Detre KM, Fishman AP, Goldring RM, Groves BM, Kernis JT, et al. Survival in patients with primary pulmonary hypertension: results from a national prospective registry. Ann Intern Med 1991;115:343- 349.

39. Aldred MA, Machado RD, James V, Morrell NW, Trembath RC. Characterization of the BMPR2 5'-untranslated region and novel mutation in pulmonary hypertension. Am J Respir Crit Care Med 2007;176:819-824. 40. den Dunnen JT. Nomenclature for the description of sequence variants; discussion [Internet]. 2002 Nov 17 [updated 2008 Feb 20; accessed 2008 Apr 14]. Baltimore, MD: Human Genome Variation Society. Available at: http://www.hgvs.org/ mutnomen/disc.html#frameshift

Benjamin Sztrymf1, Florence Coulet2, Barbara Girerd1, Azzedine Yaici1, Xavier Jais1, Olivier Sitbon1, David Montani1, Rogerio Souza1, Gerald Simonneau1, Florent Soubrier2, and Marc Humbert1

1Universite Paris-Sud 11, UPRES EA 2705, Centre National de Reference de l'Hypertension Arterielle Pulmonaire, Service de Pneumologie et Reanimation Respiratoire, Institut Paris-Sud Cytokines, Hopital Antoine-Beclere, Assistance Publique des Hopitaux de Paris, Clamart, France; and 2Universite Pierre et Marie Curie- Paris 6, Laboratoire d'Oncogenetique et Angiogenetique Moleculaire, Groupe Hospitalier Pitie-Salpetriere, Paris, France

(Received in original form December 10, 2007; accepted in final form March 20, 2008)

Supported in part by grants from the Ministere de l'Enseignement Superieur et de la Recherche and the Universite Paris-Sud 11. R.S. is supported by a grant from European Respiratory Society.

Correspondence and requests for reprints should be addressed to Marc Humbert, M.D., Ph.D., Service de Pneumologie et Reanimation Respiratoire, Hopital Antoine-Beclere, 157 rue de la Porte de Trivaux, 92140 Clamart, France. E-mail: marc.humbert@abc.aphp.fr

Am J Respir Crit Care Med Vol 177. pp 1377-1383, 2008

Originally Published in Press as DOI: 10.1164/rccm.200712-1807OC on March 20, 2008

Internet address: www.atsjournals.org

Copyright American Thoracic Society Jun 15, 2008

(c) 2008 American Journal of Respiratory and Critical Care Medicine. Provided by ProQuest Information and Learning. All rights Reserved.

Source: American Journal of Respiratory and Critical Care Medicine

More News in this Category