by Danielle Bradshaw from In The Cloud Copy

There was a case report (called Anti-MUSK positive myasthenia gravis with antiLrp-4 and antigen antibodies) released recently that talked about a patient who had three different antibodies related to myasthenia gravis.

So What Is Myasthenia Gravis?

Myasthenia gravis, or MG as it’s abbreviated, is a condition that affects the neuromuscular system. It’s an autoimmune illness that happens when a person’s immune system attacks healthy tissue and cells. The specific effect that MG has on a person’s body, however, is that it causes the voluntary muscles in the patients to become weak and fatigued. It can negatively affect muscles that enable people to breathe.

MG occurs when the neuromuscular junction (NMJ) begins to malfunction – specifically, the nerve cells and the muscles aren’t able to communicate with each other properly. In typical instances the nerve cell endings release acetylcholine (which are “signaling molecules” called neurotransmitters ) which binds to receptors on the surfaces of muscles, causing them to compress.

In a person with MG, though, acetylcholine isn’t able to simply do its job because antibodies attack the acetylcholine receptors and cause damage that stops the affected muscles from properly contracting.

A Little Info About MG and Antibodies

Antibodies against acetylcholine receptors (AChR) are, in some way, connected to around 80% of MG cases. The AChR protein is important as it is a large part of how muscles communicate. Another important protein that helps muscles “talk” to each other is muscle-specific kinase antibodies, or MuSK. This second protein is, in fact, what causes the majority of cases that don’t involve anti-AChR antibodies.

There are also lesser-known antibodies, but because they don’t appear very often, there’s still not very much information on how they function.

The Patient Report

In the report, the patient, who hails from Japan, was a 62-year-old female who was taken to the hospital after losing consciousness. Throughout the decade leading up to her trip to the hospital, she’d experienced irregular bouts of double vision, dropped head (weakness in the muscles that hold the head up), and ptosis (drooping eyelids).

By the time she’d reached the hospital, she wasn’t breathing and needed to be put on a ventilator. The patient had a battery of tests – both diagnostic and assessments – performed, so that the hospital could try to figure out what was going on with her.

The neurological exam that was performed showed that the patient’s neck and facial muscles were very weak, so much so that she was having issues swallowing. There was also a muscle biopsy done that revealed that her muscles shrank (atrophied), albeit with no inflammation. Her general examinations, like her heart, were found to be normal.

There were also anti-MuSK antibodies in her blood. Alongside those, low-density lipoprotein receptor-antigen (Lrp4) and titin were also found during the lab tests. Lrp4 is part of the NMJ signaling process, and titin helps to make up the structure of a person’s musculature.

While there are antibodies against both proteins that are linked to MG, they are fairly rare. The research team actually mentioned that this was the first time that this instance of triple antibody-positive MuSK MG has ever been recorded as far as they were aware.

Treating the Patient

The woman was then treated with a combination of high-dose methylprednisolone and tacrolimus, the latter of which is immunosuppressive. The combination of these two medicines slowly improved her breathing until they were able to take her off the ventilator. Afterward, she was then put on cyclosporine – another immune-suppressant – and pyridostigmine, which strengthens muscles.

She was able to swallow around two months into her admission to the hospital and was released soon after.

This case is one of many that involves rare MG antibodies. There is actually research that was previously conducted that has indicated that if a person shows signs of anti-MuSK and anti-Lrp4 antibodies, they likely have a more severe variation of MG which is very responsive to immune-suppressing treatments – just like this particular instance.

Anti-titin antibodies being present was notable for two reasons; it implies that both the muscles and the NMJ were being attacked by the immune system. There is also the fact that when anti-titin antibodies were reported in MG before, they were usually accompanied by anti-AChR antibodies. The latter, though, were not found in this case.

Learn more about this story here.