Overview Myasthenia gravis

Myasthenia gravis (sometimes abbreviated to MG) is a chronic, autoimmune condition that causes muscle weakness and excessive muscle fatigue. It is rare, affecting about 15 in every 100,000 people in the UK.

The condition can vary in severity and distribution of weakness between individuals, and in an individual, the symptoms can fluctuate with relapses and remissions. Myasthenia gravis can resolve spontaneously, but for most people the condition persists for life. It can be life-threatening, but with modern treatments, 90 percent become symptom-free. Myasthenia gravis presents in two main forms, ocular myasthenia gravis and generalised myasthenia gravis.

Who is at risk of developing myasthenia gravis?

Myasthenia gravis affects all races and can develop at any age from childhood to extreme old age. Young patients are more commonly women, whereas older patients, over the age of 50, are more often men. People who inherit a tendency to develop an autoimmune condition are at increased risk of developing myasthenia gravis, so a patient with myasthenia gravis may have – or have a relative with – another autoimmune condition such as diabetes or thyroid disease. Occasionally, myasthenia gravis develops in people with rheumatoid arthritis who are given the drug penicillamine. In these cases, the myasthenia gravis symptoms usually disappear when the drug is stopped.

Is myasthenia gravis inherited?

Myasthenia gravis is not an inherited condition and does not usually occur in families. This is in contrast to the congenital myasthenic syndromes that are genetic conditions (see below). However, it is thought that a person’s genetic make-up is one of perhaps many factors that lead them to develop myasthenia gravis, and it may occasionally be found in more than one family member.