The first thing to understand about amyloidosis is that it’s not a single disease, but several diseases. Just as the word “cancer” refers to a group of diseases, amyloidosis is the name for a group of diseases, too. In amyloidosis, each type is caused by the abnormal production of protein. (1) But all types of amyloidosis are very rare: it’s estimated that there are less than 200,000 people in the United States with amyloidosis.
Proteins are the human body’s building blocks, and proteins are made of chains of molecules called amino acids, according to MedlinePlus. Nearly every cell in your body gets instructions from DNA on how to build proteins from amino acids. Depending on the way these proteins assemble, they can act as chemical messengers or form muscle, bone, ligaments, tendons, or tissue, according to Science News Explores.
In some instances, the body produces an abnormal protein called amyloid, which can accumulate over time. And when enough of this amyloid builds up — either in one part of the body or in several places at once — the resulting symptoms and medical issues are known collectively as amyloidosis. (1)
“To understand amyloid, you have to understand that everything your body produces is normally biodegradable and recyclable,” says Morie Gertz, MD, an amyloidosis expert and professor of medicine at the Mayo Clinic. “Amyloid is what happens when protein loses the ability to be degraded.”
That happens because the protein molecules “misfold” and form a chemical structure that the body can’t break apart, Dr. Gertz says.
Like that big island of floating plastic in the Pacific Ocean that keeps getting bigger and bigger, the amyloid your body can’t break apart continues to accumulate and eventually causes health issues.
Collectively, the different types of amyloidosis affect fewer than 200,000 Americans, according to current estimates from the National Institutes of Health. (1) However, some experts who study the disease believe those government estimates may be way too low due to many patients being misdiagnosed or underdiagnosed. For instance, the National Organization for Rare Disorders estimates there are 4,000 new cases of AL amyloidosis, one of the most common amyloidosis types, per year. Nonetheless, experts agree that amyloidosis is a rare disease.
There are roughly 30 varieties of abnormal protein that produce amyloid and that can therefore cause amyloidosis, says Raymond Comenzo, MD, a professor at the Tufts University School of Medicine in Boston and the director of the school’s John C. Davis Myeloma and Amyloid Program. But some types of protein are more likely than others to develop abnormalities. These are the most common types of amyloidosis and some of the proteins that cause them.
AL Amyloidosis Starts in Blood Cells That Come From Bone Marrow
AL amyloidosis, also called primary amyloidosis, is one of the most common types of amyloidosis. It’s diagnosed in approximately 4,500 people each year, according to the Amyloidosis Foundation, most of whom are between ages 50 and 80. (3)
AL amyloidosis starts in the blood cells produced in bone marrow, which is a fatty substance tucked inside the hollow chambers of bones. These blood cells are responsible for making antibodies that are part of your immune system’s defenses against foreign invaders, Gertz explains.
In people with AL amyloidosis, some of these protein molecules — specifically, a kind called “light chain” proteins — don’t form properly. This improper assembly results in the buildup of amyloid. It’s not clear exactly why these protein molecules begin misassembling in the first place. (4)
The problem with amyloidosis starting in bone marrow is that the resulting amyloid can accumulate in many different parts of the body — including the heart, kidneys, and gut. As a result, AL amyloidosis can cause a number of different symptoms. These include shortness of breath or an irregular heartbeat, swelling of the legs, tingling or loss of feeling in the arms or legs, and carpal tunnel syndrome. (5)
AL amyloidosis is related to multiple myeloma, which is a type of cancer that starts in the same cells in the bone marrow. Some drugs developed to treat multiple myeloma can help people with AL amyloidosis, too. (4)
RELATED: What Are the Treatment Options for Multiple Myeloma?
Depending on how quickly someone with AL amyloidosis receives a correct diagnosis, drugs can be very effective, Gertz says. So can some types of bone marrow transplants, chemotherapy, and other symptom-specific treatments, he says. But just as AL amyloidosis symptoms vary a lot from one person with the condition to another, the prognosis also differs greatly from person to person.
Learn More About AL Amyloidosis Causes, Symptoms, and Treatment
AA Amyloidosis Is in Part the Result of Another Inflammatory Disease
Unlike most other forms of amyloidosis, AA amyloidosis tends to show up in people who have another disease — a “comorbidity.” In the case of AA amyloidosis, the comorbidities tend to be inflammatory in nature, such as rheumatoid arthritis and inflammatory bowel diseases, including ulcerative colitis and Crohn’s disease. (6)
These inflammatory diseases are in fact partly to blame for the development of AA amyloidosis. In response to inflammation, the liver produces high levels of a protein called serum amyloid A, or SAA. These SAA proteins help carry immune cells to inflamed parts of the body. But in patients who develop AA amyloidosis, the production of these SAA proteins is abnormal, and the body is unable to break apart the abnormal proteins from the healthy normal ones that carry immune cells throughout the body. (7)
The problem tends to lead to the buildup of amyloid in a person’s kidneys. This buildup often causes a cluster of symptoms known as “nephrotic syndrome,” which includes high blood pressure, fatigue, unexplained weight gain, and other symptoms that also turn up in a range of unrelated health conditions.
Other AA amyloidosis symptoms include: (7)
- Frothy urine, which is caused by high levels of protein in a patient’s pee
- High cholesterol
- Swelling of the lower legs
- Diarrhea
- Irregular heartbeat
It’s not certain how many people develop AA amyloidosis each year, but the majority of cases turn up in developing countries where serious cases of inflammation-causing infections (such as tuberculosis) are more common. (8)
AA amyloidosis can be deadly. But the average individual who develops the disease can live up to 13 years without treatment. There are a range of effective treatments for the disease, including inflammation-blocking drugs and those that slow or stop the accumulation of amyloid. Some dietary changes — including low-salt diets — can also help relieve some of the disease’s symptoms.
What Is Hereditary Amyloidosis?
Typically, amyloidosis does not run in families. But there are two types (and more than 100 subtypes) of the disease that stem from genetic mutations that result in the production of abnormal protein. These two types are known as ATTR and non-TTR amyloidosis. (9)
When to See Your Doctor About Diarrhea
Both ATTR and non-TTR amyloidosis get the “TTR” part of their name from a blood protein called transthyretin. Transthyretin is a protein that helps carry some vitamins and hormones to different parts of the body.
ATTR Amyloidosis
ATTR amyloidosis usually affects adults between the ages of 20 and 70. While it’s thought to be rare, there’s some evidence that up to 4 percent of African-Americans carry the genetic variant that causes ATTR amyloidosis. (9) The symptoms of the disease depend on where in the body the amyloid builds up.
Most cases of ATTR amyloidosis can be grouped into three categories: (10)
- Neuropathic Form of ATTR This subtype affects the nervous system. It tends to cause symptoms like nerve pain, tingling or numbness in the hands and feet, GI issues (like diarrhea and constipation), vision problems, and issues controlling bodily functions.
- Leptomeningeal Form of ATTR This subtype strikes the leptomeninges, which are layers of tissue that surround the brain and spinal cord. Stroke and bleeding of the brain are two possible complications, and symptoms include problems with coordination and balance, muscle stiffness and weakness, seizures, and dementia.
- Cardiac Form of ATTR This subtype strikes the heart and causes symptoms and side effects like an abnormal heartbeat, hypertension, and — in advanced stages — heart disease and heart failure.
Non-TTR Amyloidosis
Non-TTR amyloidosis (as its name implies) is a genetic disorder that does not have to do with transthyretin. Instead, its associated genetic variants cause the abnormal production of other proteins, many of which play a role in kidney function. This can lead to kidney damage or disease, as well as heart problems, liver problems, nerve and/or muscle pain, and other symptoms and side effects common to a wide range of health conditions. (11)
The specific treatments for the different types of ATTR and non-TTR amyloidosis depend a lot on an individual’s symptoms. Also, it’s important to note that the genetic variants that cause each of these diseases can be passed down from parent to child, but they can also form spontaneously, meaning they just show up. A person who has the gene mutation, whether inherited or spontaneous, can pass it on to his or her children. (9)
Original article: https://www.everydayhealth.com/amyloidosis/
