Pulmonary Arteriovenous Malformations in Dyskeratosis Congenita

Living-Donor Lung Transplantation for Dyskeratosis Congenita

We report the first two dyskeratosis congenita (DKC) cases, involving progressive pulmonary diseases, requiring urgent living-donor lung transplantations. Case 1: A 13-year-old boy with DKC underwent bone marrow transplantation for aplastic anemia at age of 6. He developed severe pulmonary right-to-left shunting and fibrosis. His condition deteriorated with acute fibrosis exacerbation and increased intrapulmonary shunt. He received lung transplantation and recovered uneventfully. Case 2: A 3-year-old girl with Revesz syndrome received bone marrow transplantation for refractory cytopenia. Aged six years, she had progressive hypoxia and developed a brain abscess. Her respiratory condition worsened, and recovered uneventfully after urgent lung transplantation.

An update on the biology and management of dyskeratosis congenita and related telomere biology disorders

Introduction: Telomere biology disorders (TBDs) encompass a group of illnesses caused by germline mutations in genes regulating telomere maintenance, resulting in very short telomeres. Possible TBD manifestations range from complex multisystem disorders with onset in childhood such as dyskeratosis congenita (DC), Hoyeraal-Hreidarsson syndrome, Revesz syndrome and Coats plus to adults presenting with one or two DC-related features.Areas covered: The discovery of multiple genetic causes and inheritance patterns has led to the recognition of a spectrum of clinical features affecting multiple organ systems. Patients with DC and associated TBDs are at high risk of bone marrow failure, cancer, liver and pulmonary disease. Recently, vascular diseases, including pulmonary arteriovenous malformations and gastrointestinal telangiectasias, have been recognized as additional manifestations. Diagnostics include detection of very short leukocyte telomeres and germline genetic testing. Hematopoietic cell transplantation and lung transplantation are the only current therapeutic modalities but are complicated by numerous comorbidities. This review summarizes the pathophysiology underlying TBDs, associated clinical features, management recommendations and therapeutic options.Expert opinion: Understanding TBDs as complex, multisystem disorders with a heterogenous genetic background and diverse phenotypes, highlights the importance of clinical surveillance and the urgent need to develop new therapeutic strategies to improve health outcomes.

Pulmonary arteriovenous malformations leading to hypoxemia in child with primary ciliary dyskinesia

Primary ciliary dyskinesia (PCD) is a rare genetic condition characterized by respiratory tract infections, situs inversus or heterotaxy, and male infertility. Chronic respiratory infections begin in childhood and result in complications such as bronchiectasis. As hypoxemia is often attributed to bronchiectasis, other etiologies for desaturation in this setting are not routinely evaluated. The development of pulmonary arteriovenous malformations (PAVMs) in PCD is not an established association. PAVMs as the etiology for hypoxemia may have been overlooked due to the lack of awareness of this rare association. We present a child with diagnosis of PCD with significant hypoxemia in the absence of bronchiectasis, found to have diffuse bilateral PAVMs and discuss possible physiopathologic mechanisms.

Is the Hepatic Factor a miRNA that Maintains the Integrity of Pulmonary Microvasculature by Inhibiting the Vascular Endothelial Growth Factor?

Background:

The “hepatic factor,” a molecule or group of molecules present in the hepatic venous blood, essential for the prevention of the development of pulmonary arteriovenous malfor-mations (PAVMs) and right-to-left shunting has been a conceptual enigma in the understanding of many related conditions.

Methods:

Patients with various forms of liver diseases including acute hepatic failure, and others with normal hepatic function like hereditary hemorrhagic telangiectasia (HHT), inflammatory and parasitic disorders, cardiogenic hepatopulmonary syndrome (cHPS) and skin disorders like Dyskeratosis con-genita are all known to cause PAVMs. Over a period of the last two decades our understanding of the pathogenesis of PAVMs has changed, but the mechanisms are still not clearly understood. The pres-ence of PAVMs once considered a contraindication for liver transplantation is now a cure for PAVMs in patients with HPS.

Results:

In this article the molecular mechanisms and the underlying pathogenesis of PAVMs are dis-cussed and the role of microRNA (miRNA) in its pathogenesis is favorably argued. Identifying and preventing or treating the underlying mechanisms will significantly influence the management of a large group of patients who at present cannot be effectively treated with a very poor prognosis. Progressive polycythemia, desaturation, stroke, and infection are serious complications of PAVMs.

Conclusion:

The clinical data and current understanding leads to the possible role of miRNA, which inhibits Vascular Endothelial Growth Factor (VEGF) synthesis as a pathogenic mechanism for the development of PAVMs.