Icahn School of Medicine at Mount Sinai authors of the study included, from left: Ron Do, PhD, Assistant Professor, Genetics and Genomic Sciences; Girish Nadkarni, MD, Assistant Professor of Medicine (Nephrology); and Kumardeep Chaudhary, PhD, Senior Postdoctoral Fellow, Genetics and Genomic Sciences. Dr. Nadkarni and Dr. Do are Co-Directors of the BioMe Phenomics Center.
A genetic variation that is prevalent in people of African or Hispanic/Latino ancestry was significantly associated with heart failure in a study by researchers at the Icahn School of Medicine at Mount Sinai and the Perelman School of Medicine at the University of Pennsylvania. The study, published in December 2019 in JAMA: The Journal of the American Medical Association, found underdiagnosis of affected patients and made a strong argument for wider genetic screening of the potentially deadly mutation, researchers say.
The team reported a significant association between the variation, TTR V142I, and a serious heart disorder, hereditary transthyretin amyloid cardiomyopathy (hATTR-CM). The TTR V142I gene variant, previously known as TTR V122I, causes the liver to produce misformed molecules of the transthyretin protein. The protein forms clusters, called amyloids, that can deposit in tissues throughout the body, including the nerves, kidneys, and joints. When amyloids lodge in the heart, they cause hATTR-CM, in which the walls of the heart become thicker and stiffer—in the worst case leading to heart failure.
“Using clinical data linked to the genetic data at the BioMe™ Biobank of Mount Sinai, we found that up to 4 percent of African-Americans and 1 percent of Hispanic/Latino Americans carried this mutation,” says a corresponding author of the study, Girish Nadkarni, MD, Assistant Professor of Medicine (Nephrology), and Co-Director of the BioMe Phenomics Center in The Charles Bronfman Institute for Personalized Medicine, Icahn School of Medicine. “They had a higher risk of heart failure compared to people who didn’t have this mutation, but strikingly, very few of them had been appropriately diagnosed.”
Patient Wilbert Gibson with Sumeet S. Mitter, MD, left, and Donna M. Mancini, MD, Professor of Medicine (Cardiology), and Population Health Science and Policy.
The association of the TTR V142I variant with the clinical diagnosis of heart failure was evaluated in 9,694 individuals of African and Hispanic/Latino ancestry, using health records linked to genetic data from the BioMe Biobank and the Penn Medicine Biobank. Among carriers of the TTR V142I variant, the rate of diagnosis with hATTR-CM was assessed. The findings indicated both high rates of underdiagnosis and prolonged time to the appropriate diagnosis, says senior author Ron Do, PhD, Assistant Professor of Genetics and Genomic Sciences, and Co-Director of the BioMe Phenomics Center. Only 11 percent of individuals with the genetic variant and heart failure had been diagnosed with hATTR-CM, with an average time to appropriate diagnosis of three years.
“Our hope is if we can find individuals with amyloid cardiomyopathy early through genetic screening, we can start them on therapy before a heart transplant becomes the only clinical solution,” says Sumeet S. Mitter, MD, Assistant Professor of Medicine (Cardiology), and a leader of the multidisciplinary Clinical Amyloid Program at the Icahn School of Medicine. “Early diagnosis is even more important, given recent advances in treatment for hATTR-CM.” Treatment was limited to supportive care until May 2019, when the U.S. Food and Drug Administration approved the breakthrough drug tafamidis, made by Pfizer. However, timely diagnosis is critical, since the therapy stops amyloids from depositing in tissues, but does not reverse the course of the disorder.
The experience of a Mount Sinai patient, Wilbert Gibson, is emblematic. Mr. Gibson, 63, began having worrisome symptoms in early 2019. “My weight shot up from about 170 to nearly 200 pounds.” he says. “My legs were swelling; I was having shortness of breath.” Mr. Gibson was diagnosed with cardiac amyloidosis and found to have the TTR V142I mutation. His heart failure was so advanced that he required a transplant. He received a new heart in June 2019 and says he feels restored and grateful. However, he echoes clinicians and researchers in calling for more awareness of the gene variant, its prevalence in some populations, and its association with heart failure. “People should know about this,” Mr. Gibson says.