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Doc's Tips hATTR amyloidosis

hATTR: No Longer a Rare Diagnosis

You’ve probably not heard much about amyloidosis, a group of conditions caused by the buildup in the body of misfolded transthyretin (TTR) proteins called amyloid fibrils. When the amyloid fibrils clump around the cells in an organ—brain, heart, kidney, lung—they disrupt the function of that organ. Until recently, the disease was thought to be rare.

Not only was it considered rare, but it’s often a difficult diagnosis.

That’s changing now, said Sunil Saith, M.D., clinical assistant professor at New York University Grossman School of Medicine, during the Black Health Matters Virtual Summit last month. Dr. Saith specializes in cardiac amyloidosis.

TTR is the most common form of the disease that affects the heart. The genetic form, known as hereditary amyloidosis or hATTR, affects mostly people of African descent. 

“Our understanding of this disease is emerging,” he said. For one thing, “TTR is a lot more prevalent than we’ve understood. It is found in 1 in every 25 to 30 people. Sickle cell is found in 1 in 500 African Americans. Tay-Sachs [typically found in people of Jewish descent] affects 1 in 250, cystic fibrosis 1 in 2000.”

This prevalence is what makes studying amyloidosis so important to Black health. “There are 318 million people in U.S.,” Dr. Saith said. “Of that number, 38 million identify as Black. 1.3 million of that 38 million carry the mutation that causes amyloidosis. Of that, 150,000 have been diagnosed with amyloidosis.”

To understand why so many of us have this disease, we need only look at the slave trade. Along the west coast of Africa—in the Ivory Coast, Sierra Leone and Guinea—this genetic mutation is found in much higher numbers than on other parts of the continent. Most African Americans and Afro-Caribbeans descend from these three countries. A study from London found that 10 percent of Afro-Caribbean patients with heart failure and screened for the genetic mutation that causes hATTR carried the mutation.

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What does amyloid do to the heart? “The protein enlarges the upper chambers of the heart,” Dr. Saith said. “It thickens the septum, the wall. The best analogy I have is it’s like a baseball glove. A glove is made of leather and opens and closes very easily. But imagine if you used plaster instead of leather to make that glove. It’s hard to open and close plaster.”

A few years ago, little could be done for someone who received an hATTR diagnosis. The devastating disease that makes the heart muscle thick and less efficient and which doesn’t show up until after age 50 in men and after 60 or 70 in women, had a survival rate of less than three years. “Before we were limited in options to treat it,” Dr. Saith said. 

But fortunately, that, too, is changing.

“It’s a very exciting time in amyloidosis because there are lots of treatments being investigated,” Dr. Saith said. We’ve also simplified the procedure to diagnose the disease.

The old way to diagnose amyloidosis was with an invasive heart biopsy. Now there’s a heart scan that takes 6 minutes and can be done in a doctor’s office. One therapy, patisiran, is an IV drug that directs medication to the liver and tells it to stop making the TTR protein. Tafamidis, a pill, reduces the chance of dying by 64 percent in people with early stage disease, and received FDA approval last year. A third treatment is being studied in an ongoing trial.

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Finally, the five-year Scan-MP study is in the process of recruiting elderly Black and Hispanic patients with heart failure to see how many may have hATTR. This highly sensitive combination of heart imaging and blood tests allows investigators to explore differences in genetics and sex as they relate to heart failure disease progression in the disease.

Identifying people earlier and giving them effective treatments is key. “The earlier you identify and start treatment, the better,” Dr. Saith said.

Talking to your primary care physician is also crucial. “If you’re feeling shortness of breath, if you’re feeling fatigued, if something doesn’t feel right—especially in light of a family history—talk to your doctor. We used to think this was rare, but doctors are becoming increasingly aware about it. The bottom line is having a dialogue with your primary care physician. We work with them to make appropriate referrals to a cardiologist.”

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