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1 대한내과학회지 : 제 78 권제 1 호 2010 특집 (Special Review) - 폐고혈압 유전성폐동맥고혈압과관련된유전자연구 가천의과학대학교이길여암당뇨연구원 이영재 Genetics in heritable pulmonary arterial hypertension Young Jae Lee, Ph.D. Lee Gil Ya Cancer and Diabetes Institute, Gachon University of Medicine and Science, Incheon, Korea Pulmonary arterial hypertension is caused by vascular remodeling including muscularization of arteries, loss of small precapillary arteries, and formation of neointima and plexiform lesion, resulting in a progressive increase in pulmonary vascular resistance. About 70% of heritable pulmonary arterial hypertension and 10% to 40% of idiopathic pulmonary arterial hypertension patients possess mutations in bone morphogenetic protein receptor, type 2 (BMPR2), which is a type II receptor of TGF-β superfamily. Very rarely, mutations in another receptors of TGF-β superfamily, activin-like kinase-type 1 (ALK1) and endoglin (ENG) are found in pulmonary arterial hypertension patients with hereditary hemorrhagic telangiectasia. Genetic screening is useful to identify family members who are mutation carriers in heritable pulmonary arterial hypertension families. (Korean J Med 78:20-27, 2010) Key Words: Pulmonary arterial hypertension; BMPR2 receptor; ALK1 receptor, human; ENG receptor, human; Genetic screening 서론폐동맥고혈압 (pulmonary arterial hypertension) 은휴식상태의폐동맥혈압이평균 25 mmhg 이상으로정의되는희귀질환으로연간발병률이인구백만명당 2건정도로보고되고있으며 1,2) 원인을알수없는특발성폐동맥고혈압 (idiopathic pulmonary arterial hypertension), 원인유전자가밝혀졌거나가족력이알려진유전성폐동맥고혈압 (heritable pulmonary arterial hypertension), 약품이나독극물에노출되거나결합조직병 (connective tissue diseases), HIV 감염, 문맥고혈압 (portal hypertension), 선천심장병 (congenital heart disease), 주혈흡충증 (schistosomiasis), 만성용혈빈혈 (chronic hemolytic anemia) 등과연관된폐동맥고혈압으로구분된다 3). 폐동맥고혈압환자의폐혈관에서는모세혈관이전세동맥 (precapillary arteriole) 의유실, 말초동맥 (peripheral artery) 의근육동맥화 (muscularization), 근육동맥 (muscular artery) 의비대화 (medial hypertrophy), 신생혈관내막 (neointima) 형성, 그물모양병터 (plexiform lesion) 가관찰되며이는궁극적으로우심부전 (right heart failure) 을초래하여환자를사망에이르게한다 4). 폐동맥고혈압의가족력을가진가계의존재는이질환의유전적원인을찾게하였고, 세그룹에의해 transforming growth factor-β (TGF-β) superfamily의신호전달에관여하는수용체 (receptor) 의하나인 bone morphogenic protein receptor, type II (BMPR2) 유전자가유전성폐동맥고혈압을일으키는원인유전자로보고되었다 5-7). 이후같은 TGF-β superfamily 신호전달계에속하면서유전성출혈성모세혈관확장증 (hereditary hemorrhagic telangiectasia) 를유발하는것으로알려진 activin-like kinase-type 1 (ALK1) 과 endoglin (ENG) 의일부돌

2 - Young Jae Lee. Genetics in pulmonary arterial hypertension - Figure 1. Canonical TGF-β signal transduction pathway. Human has 38 TGF-β superfamily ligands including TGF-βs, BMPs, GDFs, actvins, and inhibins. TGF-β superfamily ligands bind to the heterotetrameric receptor complexes of type II receptors (TGFBR2, BMPR2, ACVR2, ACVR2B, AMHR2) and type I receptors (ALK1-7). Type III receptors (betaglycan, endoglin) can modulate their binding. Upon binding their ligands, type II receptors phosphorylate the type I receptors which, in turn, activate downstream R-SMAD proteins. Activated R-SMADs form heteromeric complexes with Co-SMAD (SMAD4) and enter into the nucleus, where they interact with diverse transcriptional factors (TF) to regulate the expression of target genes. I-SMAD proteins inhibit TGF-β signaling downstream of type I receptors. 연변이가폐동맥고혈압을유발한다는것이 2001년과 2004년에각각보고되었다 8,9). 매우드문 ALK1과 ENG 유전자의돌연변이에의한경우를제외하면 BMPR2가가장널리알려진유전성폐동맥고혈압의원인유전자로, 전체폐동맥고혈압환자의약 6% 정도를차지하는유전성폐동맥고혈압환자의약 70% 에서 BMPR2 유전자의돌연변이가발견되었고, 연구에따라차이는있지만약 10~40% 범위의특발성폐동맥고혈압환자에서 BMPR2 유전자의돌연변이가발견되었다 10-17). BMPR2 유전자의돌연변이에따른폐동맥고혈압의평생위험도 (lifetime risk) 가 10~20% 정도로낮고자연돌연변이 (spontaneous mutation) 에의한발생을감안한다면보고된것보다높은특발성폐동맥고혈압환자가 BMPR2 유전자의 돌연변이를가지고있을것으로추정된다 18). BMPR2 유전자의돌연변이를지닌유전성폐동맥고혈압환자에서보이는낮은평생위험도로보아이질환을유발하기위해서는알려진 BMPR2 등의돌연변이외에도다른유전적, 환경적요인이관여할것으로추정되며이에따라기존에알려진유전자들외에다른유전적요인을찾기위한많은연구가수행되고있으며일부연관유전자들이보고되고있다 18). TGF-β superfamily 신호전달계지금까지확인된유전성폐동맥고혈압의원인유전자들 (BMPR2, ALK1, ENG) 은모두 TGF-β superfamily 신호전달계

3 - 대한내과학회지 : 제 78 권제 1 호통권제 593 호 (A) Genomic Structure of BMPR2 SP LBD TM KD CD (B) Protein Structure of BMPR2 Figure 2. Genomic structure (A) and protein structure (B) of BMPR2. Human BMPR2 gene consists of 13 exons encoding 1,038 amino acids. SP, signal peptide; LBD, ligand-binding domain; TM, single transmembrane domain; KD, serine/threonine kinase domain; CD, cytoplasmic domain. 에속한다 ( 그림 1). 사람에서 38개의리간드 (ligand) 가속해있는 TGF-β superfamily 는세포의성장, 분화, 이동, 사멸, extracellular matrix의형성등생명현상전반에걸쳐다양한기능을수행한다 19). TGF-β superfamily 는 TGF-βs (TGF-β1, TGF-β2, TGF-β3), BMPs, growth differentiation factors (GDFs), activins, inhibins 등의소그룹으로나뉜다. 이사이토카인 (cytokines) 들은세포막에존재하는두종류 (type I과 type II) 의 serine/threonine 키나아제 (kinase) 수용체들에결합하여세포내로신호를전달한다. Type I 수용체에는 7개의수용체 (ALK1-7) 가속하고 type II 수용체에는 5개의수용체 (TGFBR2, BMPR2, ACVR2, ACVR2B, AMHR2) 가속한다 19). TGF-β superfamily 리간드와 type I, type II 수용체들간의결합은 type III 수용체 (TGFBR3, ENG 등 ) 에의해조절되기도하며리간드와수용체의결합은항상활성화되어있는 type II 수용체의 serine/threonine 키나아제도메인 (domain) 으로하여금 type I 수용체의인산화를유도하고인산화에의해활성화된 type I 수용체는세포질내에서전달자역할을하는 SMAD 단백질들 (SMAD1-8) 을인산화시켜핵내로신호를전달하게한다 19). SMAD 단백질들은크게 receptor regulated SMAD (R-SMAD), common mediator SMAD (Co-SMAD), Inhibitor SMAD (I-SMAD) 의세그룹으로나뉘는데 R-SMAD 는 type I 수용체에의한인산화를통해활성화된후, Co-SMAD (SMAD4) 와결합하여핵내로이동해목표하는유전자들의전사 (transcription) 를조절한다. I-SMAD (SMAD6, SMAD7) 는 SMAD 단백질들에의한신호전달을방해하는역할을하는것으로알려져있다 19). 리간드-수용체의신호를직접받는 R-SMAD는신호를주는리간드와수용체에따라크게 SMAD1/5/8 그룹과 SMAD2/3 그룹으로나뉜다. BMP 와 GDF 소그룹에속하는리간드는주로 SMAD1, SMAD5, SMAD8을활성화시키고 TGF-β와 activin, inhivin 그룹에속하는리간드는 SMAD2, SMAD3를활성화시킨다 19). 하지만혈관내피세포 (endothelial cell) 에서는 TGF-β 리간드가 SMAD 1/5/8을활성화시킨다는보고처럼 TGF-β 신호전달계가반 드시이러한전달과정을따르지는않는다 20). 또한 SMAD 단백질들을통하는이러한전형적인신호전달계외에도 TGF-β superfamily 와 mitogen activated kinase (MAPK) (p38mapk, ERK1/2) 혹은 Phosphoinositide 3-kinases (PI3K) 등의다른신호전달계와의상호작용이밝혀지면서이와관련된많은연구가진행되고있다 21-23). 유전성폐동맥고혈압원인유전자들과돌연변이 1. BMPR2 BMPR2 유전자는총 13개의 exon으로구성되어있으며여기서만들어지는 1,038개의아미노산으로구성된단백질은다른 type II TGF-β 수용체들처럼신호펩타이드 (signal peptide), 리간드결합도메인 (ligand-binding domain), single transmembrane domain, serine/threonine 키나아제도메인및세포질도메인 (cytoplasmic domain) 으로이루어져있다 ( 그림 2). BMPR2 단백질이가지는한가지구조적특징은다른 type II TGF-β 수용체들과는달리전체단백질의절반정도를구성하는매우긴세포질도메인을가지는것이다. BMP 리간드는 BMPR2 단백질의 dimer 와 ALK1 (ACVL1), ALK3 (BMPR1A) 혹은 ALK6 (BMPR1B) 의 type I 단백질들의 dimer 로이루어진 heterotetrameric 수용체와결합을하고이는 SMAD1/5/8 혹은 p38 MAPK 등을통해핵내로신호를전달하게된다 19,23). 폐동맥고혈압환자의유전자검사결과가축적됨에따라지금까지 298 종류의돌연변이가폐동맥고혈압환자의 BMPR2 유전자검사결과밝혀졌다 18). 이들돌연변이는아미노산을코드하는코돈 (codon) 이유전자암호해독 (translation) 을종결하는종료코돈 (termination codon) 으로바뀌는 nonsense mutation, 다른종류의아미노산을코드하게되는 missense mutation, 한개혹은두개의뉴클레오타이드 (nucleotide) 삽입 (insertion) 및결손 (deletion) 에의한 frame-shift mutation, 스플라이싱과정에필요한뉴클레어타이드의돌연변이

4 - 이영재. 폐동맥고혈압과관련된유전자연구 - 로스플라이싱에이상이생기는 splice-site mutation, 넓은범위에서게놈 DNA의중복혹은결손 (gene duplication/deletion mutation) 등으로나뉠수있다. 이중대부분의돌연변이 (203 종류 /298종류) 가유전자암호해독과정에서완전한 BMPR2 단백질이만들어지기전에조기종료 (premature termination) 되는 nonsense mutation (85/298), frame-shift mutation (73/298), splice-site mutation (26/298), gene duplication/deletion mutation (19/298) 이며나머지가 missene muation 이다 18). 돌연변이는 BMPR2 유전자의모든 exon에서관찰되는데 serine/threonine 키나아제도메인에서가장많은돌연변이가관찰되고그외에리간드결합도메인과세포질도메인에서도다수의돌연변이가보고되었다 11,18). 유전자암호해독의조기종료와는달리 missense mutation은전체 BMPR2 단백질을코드하는 1,038개의아미노산중하나의아미노산만이바뀌는경우가대부분이므로바뀐아미노산에의해 BMPR2 단백질의기능에이상이있는경우에만 BMPR2 유전자의돌연변이로구분된다. Serine/threonine 키나아제도메인과리간드결합도메인에 80% 이상의 missense mutation이집중되어있는것으로보아이두도메인이 BMPR2 단백질의기능에중요한역할을하는것을알수있다 11,18). 이두도메인에비해수는적지만 7개의 missense mutation이세포질도메인에서발견되는데이도메인에서의 missense mutation은 SMAD 단백질을통한전형적인 TGF-β 신호전달계의과정과는무관하고대신에 p38mapk 를항상활성화시키거나 dynein light chain Tctex-type 1D (Dynlt1b) 의인산화를방해하는등의과정을통해폐동맥고혈압을유발하는것으로추정된다 24,25). 2. ALK1, ENG BMPR2 유전자의돌연변이가유전적요인에의한폐동맥고혈압의가장큰원인이지만, 이외에도유전성출혈성모세혈관확장증의원인유전자로알려진 ALK1 및 ENG의돌연변이도역시폐동맥고혈압을유발하는것으로보고되었다 8,9,18,26-28). ALK1 유전자의돌연변이중에서 16종류의돌연변이가폐동맥고혈압환자에서발견되었으며이들중 3종류를제외하면모두 serine/threonine 키나아제도메인에서발견되었다 18). 또한, ALK1 유전자에서발견되는폐동맥고혈압과관련된 16종류의돌연변이들중 13종류의돌연변이는폐동맥고혈압과일관되게연관된다 18). ENG의경우리간드결합도메인에서발견된 4종류의돌연변이가폐동맥고혈압과연관되어있다 9,18,26-28). 이들유전자의돌연변이로유발되는대부분의폐동맥고혈압은유전성출혈성모세혈관확장증을동 반하지만매우예외적으로유전성출혈성모세혈관확장증의증상없이폐동맥고혈압증상만을보이는경우가 ALK1 유전자의돌연변이를지닌환자에서보고되었다 26,28,29). 혈관벽이두꺼워지는폐동맥고혈압의혈관이상과혈관벽이얇아지는특징을보이는유전성출혈성모세혈관확장증의혈관이상은서로상반되는것처럼보이지만원인유전자들이모두 TGF-β 신호전달계특히, BMP 소그룹의신호전달계에관련된유전자들이고유전성출혈성모세혈관확장증의또다른원인유전자가 SMAD4인것으로보아혈관형성과유지에관련된이들 BMP 신호전달계의역할에연구가집중되고있다 30,31). BMP 신호전달계와폐동맥고혈압 BMP 리간드그룹은 TGF-β superfamily 에속하는여러하위그룹의사이토카인들중에서가장큰그룹으로혈관내피세포에서는 BMP2, BMP4, BMP6, BMP9, BMP10 이, 혈관민무늬근육세포 (vascular smooth muscle cell) 에서는 BMP2, BMP4, BMP6, BMP7 이역할을하는것으로알려졌다 19,32). 폐동맥의혈관내피세포에서는유전성폐동맥고혈압의원인이되는 BMPR2, ALK1, ENG 모두가다량발현되고있으며이들은주로 BMP9 과 BMP10, 특히 BMP9 의신호를전달하여 SMAD1/5/8을인산화시키고혈관내피세포의증식및세포자멸사 (apoptosis) 를억제하는것으로알려졌다 33,34). 실제로 BMPR2 돌연변이를가지고있는환자의혈관에서는 BMPR2 의발현이현저히감소되어있으며 35) 이러한감소정도는 BMPR2 돌연변이를가진한대립유전자 (allele) 로인한감소보다심하기에또다른유전적혹은환경적요인이관여하는것으로생각되어 second hit 가설이제기되었다 36,37). 또한, BMPR2 돌연변이가찾아지지않은특발성폐동맥고혈압환자의혈관에서도역시 BMPR2 발현감소가관찰되었다 36). 이러한 BMPR2 의감소는혈관내피세포의세포자멸사를촉진하여모세혈관이전세동맥을잃게하거나이러한세포자멸사에저항할수있는혈관내피세포들의비정상적인증식으로인한그물모양병터의형성을유도하는것으로추정된다 4). 비록혈관내피세포보다는발현양이적지만혈관내피세포에서만특이적으로발현되는 ALK1, ENG와는달리 BMPR2는혈관민무늬근육세포에서도발현되며 BMP2 및 BMP4 의신호를전달하여혈관민무늬근육세포의증식을억제한다. 그러므로 BMPR2가감소된혈관계에서는혈관내피세포의세포자멸사가증가하여혈관내피세포막에이상이생

5 - The Korean Journal of Medicine: Vol. 78, No. 1, 기고이로인해증식억제에문제가생긴혈관민무늬근육세포들이성장인자 (growth factor) 에노출되어비정상적인말초동맥의근육동맥화, 근육동맥의비대화등이일어난다는가설이제시되었다 36). 폐동맥고혈압의동물모델 BMP신호전달계의이상이폐동맥고혈압을일으키는기전을세포수준이아닌 in vivo 상태에서조사하기위해몇가지동물모델이만들어졌다. 두대립유전자를모두불능화시킨 homozygous BMPR2 (BMPR2 -/- ) 생쥐는배아의초기발생과혈관형성의이상으로죽고 38) 폐동맥고혈압환자처럼한대립유전자만을불능화시킨 heterozygous BMPR2 (BMPR2 +/- ) 생쥐는정상생쥐와차이를보이지않지만 39) 폐에서 interleukin-1를과발현시키거나 40) 세로토닌 (serotonin) 을주입했을때 39) 정상대조군에비해높은빈도로폐고혈압증상을보였다. 유전적요인을조사하기위해우리는 BMPR2 유전자를혈관내피세포특이적으로불능화시킬수있는생쥐를이용하였다 41). 이결과정상대조군에서는우심실수축기압 (right ventricular systolic pressure) 이모두 30 mmhg 이하인데비해 BMPR2의한대립유전자가혈관내피세포에서불능화된경우 20%, 두대립유전자모두가불능화된경우는 39% 의생쥐에서 30 mmhg 이상의비정상적인우심실수축기압이관찰되었으며이러한이상수축기압을보이는생쥐에서만우실비대, 말초동맥의비대화및근육동맥화증상을볼수있었다. 이러한동물모델을이용한실험들은 BMPR2 유전자의돌연변이에따른폐동맥고혈압의평생위험도가 10~20% 정도로낮은것과더불어 BMPR2 유전자의돌연변이를지닌사람에서폐동맥고혈압이유발되기위해서는또다른유전적혹은환경적요인이필요하다는 second-hit 가설을지지하는결과이다. 폐동맥고혈압연관유전자확실한유전성폐동맥고혈압을보이는가계의유전자검사에서기존에알려진원인유전자인 BMPR2, ALK1, ENG의돌연변이가밝혀지지않은것은 promoter 혹은 enhancer 부위처럼이들유전자들에대한유전자검사범위를넘어선위치에서의돌연변이가능성을제외하더라도다른원인유전자혹은 modifier 유전자의존재를배제할수없게하며실제로여러후보유전자들이조사되고있다. 폐동맥민무늬근육 세포에서막전위 (membrane potential), 혈관긴장도 (vascular tone), 증식, 세포자멸사등에관여하는 potassium voltagegated channel, shaker-related subfamily, member 5 (KCNA5) 42), 폐혈관수축및민무늬근육세포의증식에관여하는 serotonin의수송체인 solute carrier family 6 (neurotransmitter transporter, serotonin), member 4 (SLC6A4) 43-45), 혈관확장및항응집제로서의기능을지닌 prostacyclin의생합성과정에필요한 prostaglandin I2 (prostacyclin) synthase (PTGIS) 46), angiotensin I을혈관수축기능을하는 angiotensin II로만드는 angiotensin I converting enzyme (peptidyl-dipeptidase A) 1 (ACE) 47,48), R-SMAD 의하나인 SMAD8 49) 등이그예이다. 유전자검사및유전상담 1. 유전자검사방법폐동맥고혈압의원인유전자로알려진 BMPR2, ALK1, ENG의유전자검사는 BMPR2에대해우선적으로실시되며유전성출혈성모세혈관확장증의증세가보일경우 ALK1과 ENG 유전자에대한검사를실시하게된다. 검사방법은대상유전자의 exon과스플라이싱 (splincing) 과정에필요한 exon 주변의 splice-site를포함하는게놈 DNA (genomic DNA) 를중합효소연쇄반응 (Polymerase Chain Reaction, PCR) 을이용하여증폭하고직접적인유전자염기서열분석을통해돌연변이를찾아낸다. 이러한방법으로찾아낼수없는넓은범위의유전자중복및결손 (gene duplication/deletion mutation) 은 melting curve analysis, denaturing high-performance liquid chromatography, Southern blotting, multiplex ligation-dependent probe amplification (MLPA) 50) 등의방법으로찾아낸다. 이들방법중 MLPA 방법은한번의실험으로 BMPR2, ALK1, ENG 세유전자의 exon 부위가얼마나샘플내에존재하는지를알수있어정상인의샘플과환자의샘플을비교함으로써넓은범의의유전자결함을알수있어 exon에대한염기서열분석으로돌연변이를찾지못한경우의초기스크리닝방법으로많이사용되고있다. 2. 유전상담대상으로하는유전병의유전형과질환사이에높은상관관계가있고유전검사에의한유전병의조기발견이질환의치료에많은도움을주는경우유전자검사와환자와의유전상담 (genetic counseling) 은매우효과적이다. 하지만폐동맥고혈압환자의경우 13개의 exon으로구성된매우긴

6 - Young Jae Lee. Genetics in pulmonary arterial hypertension - BMPR2 유전자를조사해야하는기술적인문제를포함해서돌연변이를가지더라도 10~20% 의낮은발병률을보이고돌연변이를가진것을미리알게되더라도실질적으로폐동맥고혈압의발생을막을방법이없는이질환의특성상유전자검사와유전상담에어려움이있다. 하지만아직발병하지않은가계원에대해지속적인폐동맥고혈압검사가필요한유전성폐동맥고혈압을지닌가계의경우유전자검사를통해돌연변이를가지지않은가계구성원을이검사에서제외할수있는장점이있다. 또한특발성폐동맥고혈압환자에서의유전자검사는 BMPR2 혹은다른원인유전자의돌연변이에의한폐동맥고혈압의가능성을검사할수있어가계구성원의폐동맥고혈압조기진단에도움을줄수있다. 유전자검사가지니는여러장점에도불구하고검사의결과는가계구성원들간에많은정신적문제를야기할수있으므로유전상담은많은주의를필요로한다. 중심단어 : 폐동맥고혈압 ; BMPR2; ALK1; ENG; 유전자검사 REFERENCES 1) Gaine SP, Rubin LJ. Primary pulmonary hypertension. Lancet 352: , ) Humbert M, Sitbon O, Chaouat A, Bertocchi M, Habib G, Gressin V, Yaici A, Weitzenblum E, Cordier JF, Chabot F, Dromer C, Pison C, Reynaud-Gaubert M, Haloun A, Laurent M, Hachulla E, Simonneau G. Pulmonary arterial hypertension in France: results from a national registry. Am J Respir Crit Care Med 173: , ) Simonneau G, Robbins IM, Beghetti M, Channick RN, Delcroix M, Denton CP, Elliott CG, Gaine SP, Gladwin MT, Jing ZC, Krowka MJ, Langleben D, Nakanishi N, Souza R. Updated clinical classification of pulmonary hypertension. J Am Coll Cardiol 54:S43-54, ) Rabinovitch M. Molecular pathogenesis of pulmonary arterial hypertension. J Clin Invest 118: , ) Deng Z, Morse JH, Slager SL, Cuervo N, Moore KJ, Venetos G, Kalachikov S, Cayanis E, Fischer SG, Barst RJ, Hodge SE, Knowles JA. Familial primary pulmonary hypertension (gene PPH1) is caused by mutations in the bone morphogenetic protein receptor-ii gene. Am J Hum Genet 67: , ) International PPH Consortium, Lane KB, Machado RD, Pauciulo MW, Thomson JR, Phillips JA 3rd, Loyd JE, Nichols WC, Trembath RC. Heterozygous germline mutations in BMPR2, encoding a TGF-beta receptor, cause familial primary pulmonary hypertension. Nat Genet 26:81-84, ) 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 345: , ) Trembath RC, Thomson JR, Machado RD, Morgan NV, Atkinson C, Winship I, Simonneau G, Galie N, Loyd JE, Humbert M, Nichols WC, Morrell NW, Berg J, Manes A, McGaughran J, Pauciulo M, Wheeler L. Clinical and molecular genetic features of pulmonary hypertension in patients with hereditary hemorrhagic telangiectasia. N Engl J Med 345: , ) Chaouat A, Coulet F, Favre C, Simonneau G, Weitzenblum E, Soubrier F, Humbert M. Endoglin germline mutation in a patient with hereditary haemorrhagic telangiectasia and dexfenfluramine associated pulmonary arterial hypertension. Thorax 59: , ) 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 107: , ) Machado RD, Aldred MA, James V, Harrison RE, Patel B, Schwalbe EC, Gruenig E, Janssen B, Koehler R, Seeger W, Eickelberg O, Olschewski H, Elliott CG, Glissmeyer E, Carlquist J, Kim M, Torbicki A, Fijalkowska A, Szewczyk G, Parma J, Abramowicz MJ, Galie N, Morisaki H, Kyotani S, Nakanishi N, Morisaki T, Humbert M, Simonneau G, Sitbon O, Soubrier F, Coulet F, Morrell NW, Trembath RC. Mutations of the TGF-beta type II receptor BMPR2 in pulmonary arterial hypertension. Hum Mutat 27: , ) Cogan JD, Vnencak-Jones CL, Phillips JA 3rd, Lane KB, Wheeler LA, Robbins IM, Garrison G, Hedges LK, Loyd JE. Gross BMPR2 gene rearrangements constitute a new cause for primary pulmonary hypertension. Genet Med 7: , ) Aldred MA, Vijayakrishnan J, James V, Soubrier F, Gomez-Sanchez MA, Martensson G, Galie N, Manes A, Corris P, Simonneau G, Humbert M, Morrell NW, Trembath RC. BMPR2 gene rearrangements account for a significant proportion of mutations in familial and idiopathic pulmonary arterial hypertension. Hum Mutat 27: , ) Thomson JR, Machado RD, Pauciulo MW, Morgan NV, Humbert M, Elliott GC, Ward K, Yacoub M, Mikhail G, Rogers P, Newman J, Wheeler L, Higenbottam T, Gibbs JS, Egan J, Crozier A, Peacock A, Allcock R, Corris P, Loyd JE, Trembath RC, Nichols WC. Sporadic primary pulmonary hypertension is associated with germline mutations of the gene encoding BMPR-II, a receptor member of the TGF-beta family. J Med Genet 37: , ) Souza R, Humbert M, Sztrymf B, Jaïs X, Yaïci A, Le Pavec J, Parent F, Hervé P, Soubrier F, Sitbon O, Simonneau G. Pulmonary arterial hypertension associated with fenfluramine exposure: report of 109 cases. Eur Respir J 31: , ) Aldred MA, Machado RD, James V, Morrell NW, Trembath RC

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