AL (Light Chain) Amyloidosis: Symptoms, Causes, Treatment, and More

Immunoglobulin light chain amyloidosis (most often referred to as AL amyloidosis) is a rare disease caused by the buildup of abnormal proteins in the body.

About 4,000 people are diagnosed with this disease each year, most of them between the ages of 50 and 65 — and they make up about 78 percent of new amyloidosis cases. (1,2) In the past, AL amyloidosis was sometimes called “primary” amyloidosis because it’s the most common type of the disease.

Like other types of amyloidosis, AL involves the accumulation of protein molecules. But unlike other types of the disease, the problem stems from a bone marrow disorder. (3)

The symptoms people with AL amyloidosis experience depend on which organs of the body are affected (they range from diarrhea and numbness in the hands or feet to difficulty swallowing and irregular heartbeat). And if left untreated or mismanaged, AL amyloidosis — like other forms of the disease — can cause organ failure, making it a potentially fatal disease.

What Causes AL Amyloidosis, and Why Do People Get It?

Bone marrow is a soft and fatty substance tucked inside bones that is responsible for making certain types of blood cells, including plasma cells. (3) And it’s our bodies’ plasma cells that make antibody proteins, which your immune system uses to protect you against unwanted bacteria, viruses, or other pathogens that find their way into your system.

In patients with AL amyloidosis, the bone marrow’s plasma cells make abnormal antibodies. Specifically, some of the “light” protein molecule chains that make up these antibodies don’t fold properly, says Morie Gertz, MD, a hematologist and oncologist and a professor of medicine at Mayo Clinic in Rochester, Minnesota, who specializes in amyloidosis.

The misfolding causes the abnormal protein to be produced, build up, and form amyloid deposits, Dr. Gertz says. (The “AL” in AL amyloidosis stands for “amyloid” and “light chain.”) Once that buildup starts, it tends not to stop without medical intervention.

Even though the abnormal proteins are the result of a disorder in the bone marrow, the amyloid tends to accumulate and cause problems elsewhere in the body. This can occur around tissues, organs, or nerves. (3) And because of its wide-ranging effects, AL amyloidosis is known as a “systemic” form of the disease. (1)

There are two different subtypes of AL amyloidosis, known as “kappa” and “lambda.” They differ based on which one of the two light chain protein molecules is abnormally produced and accumulates. Patients may be told which subtype they have, though at this point treatment methods are the same for both, according to a 2018 paper. (3,4

AL Amyloidosis Signs and Symptoms Can Show Up in Many Parts of the Body

Because AL amyloidosis can (and often does) affect many different parts of the body at once, its symptoms or “presentations” can be quite different from one individual with the disorder to another. (5) But some common and general symptoms of AL amyloidosis are fatigue, unexplained weight loss, and swelling in one or more parts of the body. (3)

These are all what doctors call nonspecific symptoms — meaning they’re common in a range of diseases, and so experiencing one or even all of them doesn’t mean someone has AL amyloidosis. (5)

Along with these general symptoms, AL amyloidosis may cause symptoms, side effects, and complications in these parts of the body:

  • Heart Along with the kidneys, the heart is the organ most commonly affected by AL amyloidosis. Many AL amyloidosis patients have significant amyloid buildup in their heart. The buildup of amyloid causes stiffness in the walls of the heart and poor function, which can lead to shortness of breath or an unusually fast or slow heartbeat (arrhythmia). It can also cause rapidly progressive congestive heart failure, which is one of the tell-tale signs of AL cardiac amyloidosis. (1,3)
  • Kidneys Because amyloid proteins interfere with the kidneys’ ability to filter out toxins, chronic kidney disease is common among patients with AL amyloidosis. Improper kidney function due to amyloidosis can also lead to swelling in the legs (edema), the belly, and the arms. (3)
  • Gut In the digestive system, amyloid deposits can lead to nausea, diarrhea, constipation, loss of appetite, or feeling full after eating even small amounts of food. (Again, these symptoms are common to many other GI issues as well, so just because you experience them does not necessarily mean you have amyloidosis.) (3)
  • Nervous System Numbness, tingling, and pain are all potential symptoms if amyloid deposits affect the nervous system. Another nervous system symptom is loss of sensitivity to heat or cold, as well as dizziness and nausea. (3)
  • More Symptoms Carpal tunnel syndrome and a swollen or enlarged tongue can turn up in some people with AL amyloidosis, as can unexplained bruising — especially around the eyes. “Shoulder pad syndrome” can also occur, which is the swelling of the shoulder in response to amyloid tissue deposits. (1,3)

RELATED: Everything You Should Know About Heart Disease

Is AL Amyloidosis a Cancer?

AL amyloidosis is commonly associated with multiple myeloma because both conditions stem from the malfunctioning plasma cells in the bone marrow. But for multiple myeloma, the problems stem from the abnormal growth of these cells in the bone marrow, whereas for AL amyloidosis the problems arise as a consequence of the buildup of amyloid protein these malfunctioning cells produce. But about 15 percent of myeloma patients do also acquire AL amyloidosis. (3,6)

The close relationship to multiple myeloma is actually a good thing for people with AL amyloidosis. Why? Some drug treatments initially developed to treat myeloma have turned out to also help amyloidosis patients. “Many treatment advances have come from advancements for multiple myeloma, where there’s a lot more research funding,” Gertz says.

With the Correct Diagnosis and Treatment, AL Amyloidosis Can Be Managed

Because the disease is uncommon and its symptoms are nonspecific, AL amyloidosis patients may struggle for years to get an accurate diagnosis, Gertz says. Some never do. A urine or blood test for excessive amyloid protein deposits is one way to spot the disease, he says. Follow-up biopsies of affected tissue can confirm the presence of amyloid deposits.

RELATED: What You Need to Know About Amyloidosis Diagnosis

Depending on how early a doctor identifies AL amyloidosis, drug treatments can be very effective, Gertz says. So can stem cell transplant procedures, chemotherapy, and some treatments that target the affected organs.

But for other people, AL amyloidosis can be a fatal disease, Gertz says. “It can be a very bad disease if not recognized until organ failure is advanced,” he says. How long that takes depends on the patient and the affected organ. Typically, 12 to 18 months will pass before amyloid buildup in the heart becomes fatal, while a patient with an affected kidney could live for 5 to 10 years, according to Gertz.

However, AL amyloidosis can affect a person in many different ways. Treatment and outcomes vary a lot from one patient to the next. That said, advances in science and medicine have markedly improved survival rates in the last 40 years. Patients today can live for 3 times as long after diagnosis as patients in the 1980s (a median of 4.6 years versus 1.4 years, respectively). (7)

But getting diagnosed early can significantly improve outcomes, so talk to your doctor if you have symptoms that might be consistent with AL amyloidosis. (8)

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