May 16, 2011
JHU geneticist elected to National Academy of Sciences
Harry C. “Hal” Dietz III, the Victor A. McKusick Professor of Genetics and Medicine at the McKusick-Nathans Institute of Genetic Medicine at Johns Hopkins and an investigator of the Howard Hughes Medical Institute, is one of 72 new members of the National Academy of Sciences, an honorary society that advises the government on scientific matters.
“This recognition could not have gone to a more deserving clinician-scientist,” said David Valle, the Henry J. Knott Professor and director of the McKusick-Nathans Institute. “His team has over the years made such great strides in understanding and treating Marfan syndrome, and his work defines translational medicine.”
Dietz, a pediatric cardiologist and geneticist at Johns Hopkins, also directs the William S. Smilow Center for Marfan Syndrome Research at Johns Hopkins and has devoted his career to understanding and improving quality of care for children with Marfan syndrome. Marfan is a potentially fatal connective tissue disease that may have affected Abraham Lincoln and Charles de Gaulle, among others, and causes an enlargement of the aorta, the major blood vessel leaving the heart, making it likely to tear or burst. While Marfan affects only one in 5,000 Americans, enlargement of the aorta kills up to 2 percent of people in developed countries.
Through family studies in the late 1980s, Dietz’s research team linked an error in the gene that encodes fibrillin-1, a connective tissue protein, to Marfan syndrome. The investigators have since found or helped find the genes underlying four other conditions that cause aortic aneurysms, including Loeys-Dietz syndrome, which is named after Dietz and another Johns Hopkins scientist, Bart Loeys. Children with the syndrome, which can cause the aorta to rupture at a very early age, were previously thought to have Marfan syndrome or some unspecified connective tissue disorder.
In the 1990s, working with mice engineered to lack the fibrillin-1 gene, Dietz’s team discovered that the mice showed typical Marfan symptoms. It also discovered that the fibrillin-1 protein shared a remarkable resemblance to another protein that acts to dampen the activity of transforming growth factor-beta. By injecting fibrillin-1-lacking mice with an antibody that blocks TGF-beta the researchers were able to alleviate the Marfan-like symptoms, suggesting that drugs that could block TGF-beta might be viable treatments for Marfan syndrome.
As it turns out, losartan (Cozaar), which is used to treat high blood pressure, blocks TGF-beta activity and had already been approved by the FDA, and in 2007, a clinical trial was launched to test losartan for its ability to slow aortic growth.
“I am truly honored to be elected to the National Academy of Sciences and particularly proud to receive this recognition from my peers,” Dietz said. “I owe a great debt of gratitude to the superb clinical and research community at Johns Hopkins and share this great honor with all of the young scientists in my lab.”