Two separate groups of scientists funded by the National Heart, Lung, and Blood Institute (NHLBI) of the National Institutes of Health have simultaneously identified a genetic mutation associated with primary pulmonary hypertension (PPH), a rare but devastating lung disease.
The two groups, the International PPH Consortium (investigators from Vanderbilt University, Nashville; Children's Hospital Medical Center, Cincinnati; Indiana University School of Medicine, Indianapolis; and the University of Leicester, UK.) and Columbia University investigators, independently reported that defects in the BMPR2 gene, which regulates growth and development of the lung, are associated with PPH. The defects in the gene lead to the abnormal proliferation of cells in the lung characteristic of PPH.
Although both studies suggest that only one gene is involved in PPH, neither group identified the defects in BMPR2 as the sole cause of PPH. In addition, since many people without a known family history of PPH get the disease, both groups suggested that other factors may interfere with control of tissue growth.
One report was released today on the Web site of Nature Genetics. The other report was released on July 20th on the Web site of the American Journal of Human Genetics.
Said NHLBI Director Dr. Claude Lenfant, "This research is the culmination of nearly 20 years of work to identify possible immunologic and genetic factors in the cause and progression of PPH. Now that we have pinpointed a gene, we can focus on learning how it works. That information should enable us to devise better treatments and perhaps eventually a preventive therapy or cure."
PPH is a rare lung disease characterized by uncontrolled proliferation of cells in the blood vessels in the lungs. This build-up of cells leads to blockages in the blood vessels, forcing the heart to pump harder and increasing blood pressure in the pulmonary artery. The disease affects twice as many women as men – usually women of child-bearing age -- although it can occur at any age, including infancy.
The most common forms of treatment for advanced PPH are lung transplantation and continuous intravenous administration of prostacyclin to dilate or relax blood vessels. These treatments are expensive and difficult, and side effects are common. Before the availability of these treatments, survival following diagnosis of PPH was only 3 to 5 years. Even with treatment, life expectancy for PPH patients is very limited.
The NHLBI created the first PPH Patient Registry in the world in 1981 to gain an understanding of the natural course of PPH. Some of the 194 patients in the Registry participated in the Consortium and Columbia studies. Both groups studied patients from all over the world.
The next step will be to determine whether people with sporadic PPH, where there does not appear to be a family history, carry the same defect.
For additional information, contact the NHLBI Communications Office at 301-496-4236. To obtain a faxed copy of the paper, call Lynn Bhajan, Nature Genetics, 212-726 9200. Online copies of the papers can be accessed by registered users at the following two Web sites: Nature Genetics (http://press.nature.com/index2.html) and the American Journal of Human Genetics (http://www.cell.com/AJHG/).
More information about Primary Pulmonary Hypertension and other lung diseases is available online on the NHLBI Web site (http://www.nhlbi.nih.gov).