Avances en la genética de la hipertensión arterial pulmonar

La hipertensión arterial pulmonar (HAP) es un trastorno cardiopulmonar grave e incurable que conlleva una importante morbilidad y mortalidad. Se caracteriza por la oclusión y remodelación de las arteriolas pulmonares, insuficiencia respiratoria progresiva, disfunción ventricular derecha, insuficiencia cardíaca y muerte prematura. Puede presentarse en diferentes formas, entre ellas la idiopática (HAPI) en ausencia de una causa conocida y la hereditaria (HAPH) en caso de relacionarse con una alteración genética o si hay agregación familiar. Existen además de estas formas, otras causas de HAP asociadas a diversas condiciones médicas (drogas, toxinas, infección por virus de la inmunodeficiencia humana -VIH-, etc.). A pesar de los avances recientes sigue siendo una enfermedad difícil de diagnosticar y tratar. La investigación de las bases genéticas de la HAP ha contribuido significativamente a mejorar la comprensión de esta patología. Las alteraciones genéticas más frecuentes asociadas a la HAP son mutaciones inactivantes del gen que codifica el receptor de la proteína morfogenética ósea tipo 2 (BMPR2, bone morphogenic protein receptor type 2). Los pacientes con HAP y mutaciones en BMPR2 se presentan a una edad más temprana con una enfermedad más grave y tienen un mayor riesgo de muerte o trasplante, que aquellos sin mutaciones. Avances recientes han conducido al descubrimiento de nuevos genes relacionados con la HAP, tales como ACVRL1 (activin A receptor like type 1), ENG (endoglin), CAV1 (caveolin-1), KCNK3 (potassium channel subfamily K, member 3), entre otros. En este artículo de revisión resumimos el conocimiento sobre las variantes genéticas raras y comunes que subyacen al desarrollo y pronóstico de la HAP. Además, esbozamos la importancia de implementar el asesoramiento y el estudio genético en centros especializados. La comprensión de la genética de la HAP proporcionará nueva información sobre los mecanismos subyacentes a la patobiología, potencialmente, útiles para desarrollar nuevas estrategias terapéuticas en el marco de una medicina personalizada.

Pulmonary arterial hypertension (PAH) is a serious and incurable cardiopulmonary disorder with significant morbidity and mortality. It is characterized by the occlusion and remodeling of the pulmonary arterioles, progressive respiratory failure, right ventricular dysfunction, heart failure and premature death. PAH can occur in different forms, including idiopathic (IPAH) in absence of a known cause and hereditary (HPAH) if related to a genetic alteration or if there is familial aggregation. Besides these forms, there are other causes of PAH associated with various medical conditions (drugs, toxins, HIV infection, etc.). Despite recent advances in PAH, it remains a challenging disease to both diagnosis and management. Research about the genetic basis of PAH has contributed significantly to improve the understanding of this condition. The most common genetic alterations associated with PAH are inactivating mutations in the gene encoding a bone morphogenetic protein receptor type 2 (BMPR2). Patients with BMPR2 mutations present PAH at a younger age with more severe disease, and have an increased risk of death or transplantation, than those without mutations. Recent advances have led to the discovery of new genes related to PAH, such as ACVRL1 (activin A receptor like type 1), ENG (endoglin), CAV1 (caveolin-1), KCNK3 (potassium channel subfamily K, member 3), among others. In this review, we summarize the knowledge about rare and common genetic variants that underlie PAH development and prognosis. Additionally, we outline the importance of implementing genetic counseling and testing in specialized pulmonary hypertension centers. Understanding the genetics of PAH will provide new insights into the mechanisms underlying its pathobiology potentially useful for developing new therapeutic strategies within the scope of a personalized medicine.

A hipertensão arterial pulmonar (HAP) é um distúrbio cardiopulmonar grave e incurável, com morbidade e mortalidade significativas. É caracterizada pela oclusão e remodelação das arteríolas pulmonares, insuficiência respiratória progressiva, disfunção ventricular direita, insuficiência cardíaca e morte prematura. Pode acontecer em diferentes formas, incluindo a idiopática (HAPI) na ausência de uma causa conhecida e a hereditária (HAPH) no caso de estar associada a uma anomalia genética ou quando há agregação familiar. Adicionalmente a estas formas, existem outras causas de HAP associadas a várias condições médicas (toxinas, drogas, infecção por HIV, etc.). Apesar dos avanços recentes, continua a ser uma doença difícil de diagnosticar e tratar. A pesquisa sobre a base genética da HAP contribuiu significativamente para melhorar a compreensão desta doença. As alterações genéticas mais comuns associadas à HAP são as mutações no gene que codifica o receptor da proteína morfogenética óssea tipo 2 (BMPR2, bone morphogenic protein receptor type 2). Pacientes com HAP e mutações BMPR2 se apresentam em idade mais jovem com doença mais grave e têm maior risco de morte ou transplante do que aqueles sem mutações. Avanços recentes levaram à descoberta de novos genes relacionados à HAP, tais como ACVRL1 (activin A receptor like type 1), ENG (endoglin), CAV1 (caveolin-1), KCNK3 (potassium channel subfamily K, member 3), entre outros. Neste artigo de revisão resumimos o conhecimento sobre as variantes genéticas raras e comuns associadas à etiologia e prognóstico da HAP. Ademais, destacamos a importância de implementar o aconselhamento genético e o estudo genético em centros especializados. A compreensão da genética da HAP vai proporcionar novo informação sobre os mecanismos subjacentes à patobiologia potencialmente úteis para o desenvolvimento de novas estratégias terapêuticas no âmbito da medicina personalizada.

Genetic variants in a Polish population of patients with pulmonary arterial hypertension: sequencing of BMPR2, ALK1, and ENG genes.

BACKGROUND: Pulmonary arterial hypertension (PAH) is a rare disease with a very serious prognosis. It seems that mutations in genes related to transforming growth factor-b signalling pathway are often related to the development of the disease. No study covers this problem in a Polish population. AIM: To screen for genetic mutations in a Polish cohort of patients with pulmonary hypertension, especially with idiopathic PAH, treated in a single hospital in Poland. METHODS: DNA sequencing method was used. Samples from 50 patients with pulmonary hypertension were screened for mutations in type 2 bone morphogenetic protein receptor of the transforming growth factor-b superfamily gene (BMPR2). Samples from 20 patients with idiopathic PAH (11 men, mean age 55 years) were also screened for mutations in activin A receptor-like type 1 gene (ALK1) and endoglin gene (ENG). RESULTS: No genetic variations were found for the BMPR2 gene. In all 20 samples from idiopathic pulmonary hypertension patients we found heterozygosity of single nucleotide polymorphism (SNP) rs 372023206 in ALK1 gene. Three samples from these patients showed variations of ENG gene: we found one sample with heterozygosity of SNP rs 200525684, one with heterozygosity of SNP rs 3739817, and one with both. CONCLUSIONS: We detected benign polymorphisms or genetic variants of unknown importance. It is possible that the Polish population of PAH patients differs from the previously described populations of other countries in terms of the frequency and importance of mutations in BMPR2, ALK1 and ENG genes.

Genetics in pulmonary arterial hypertension in a large homogeneous Japanese population.

Pulmonary arterial hypertension (PAH) is a rare but serious disease with a grave prognosis. Bone morphogenetic protein type 2 receptor (BMPR2) gene is a strong pathogenic factor for PAH. As a collaborative team from Kyorin University and Keio University in Japan, we have analyzed the BMPR2 gene in 356 probands and more than 50 family members, including secondary patients. Importantly, the study population is a racially, ethnically, and socially homogeneous population. In PAH patients, there is a high incidence of unique mutations in BMPR2, and several mutations are frequently observed in the Japanese population, suggesting that these common and recurring mutations may be highly pathogenic or have high penetrance, explaining why they are found frequently throughout the world. We have also mapped each breakpoint of exonic deletions/duplications and found that most break and rejoining points are in the Alu elements. Reviewing the distribution of the reported mutations on each exon of BMPR2 revealed that the number and frequency of mutations are imbalanced among exons. The penetrance of BMPR2 gene mutations was 3-fold higher in females than males. Full elucidation of BMPR2-mediated pathogenic mechanisms in PAH requires persistent efforts to achieve precision or individualized medicine as a therapeutic strategy for PAH.

De novo mutations in the BMPR2 gene in patients with heritable pulmonary arterial hypertension.

A substantial proportion of patients with pulmonary arterial hypertension (PAH) have mutations in the Bone Morphogenetic Protein Receptor type-2 (BMPR2) gene. PAH due to BMPR2 mutations is inherited as an autosomal dominant trait with several unique features, including a wide variety of mutations, reduced penetrance, a skewed gender ratio, variable expressivity and genetic anticipation. To address the genetic background of these unique features of BMPR2 mutation, we conducted a systematic analysis of 15 PAH families with BMPR2 mutation. The exonic protein coding sequence of BMPR2 was amplified by polymerase chain reaction and the products were sequenced directly to detect point mutations in BMPR2. Parental identification was carried out to confirm the parental relationship using multiplex 15 loci analysis. Combining mutation detection in family members with parental identification, we described three cases of de novo mutation in the BMPR2 gene by different modes in a PAH family. These de novo mutations may account for the wide variety of mutations in BMPR2. Taken together with the juvenile onset of the disease, there is possibly some balance of de novo mutations and untransmittable mutations which keeps the frequency of PAH low in the general population.