SNP Shot: Genomic Insights

Myasthenia gravis is a condition that weakens skeletal muscles, the muscles responsible for body movement. This weakness often begins in the eye muscles, leading to droopy eyelids (ptosis) and difficulty coordinating eye movements, resulting in blurred or double vision. When the weakness is limited to the eye muscles, it's known as ocular myasthenia. However, in most cases, the weakness extends to other muscles in the face and neck. This can cause unusual facial expressions, difficulty holding the head up, speech problems (dysarthria), and difficulty chewing and swallowing (dysphagia), potentially leading to choking, gagging, or drooling.

In some individuals with myasthenia gravis, muscles in the arms and legs can also be affected. This can lead to changes in gait or difficulty with tasks like lifting objects, standing up from a seated position, or climbing stairs. The muscle weakness tends to vary, generally worsening with activity and improving with rest.

Weakness in the chest wall muscles and the diaphragm (the muscle separating the abdomen and chest) can cause breathing difficulties in some individuals with myasthenia gravis. Approximately 10% of people with the disorder experience a potentially life-threatening complication where these respiratory muscles become so weak that breathing is severely impaired, requiring ventilation support. This respiratory failure, known as a myasthenic crisis, can be triggered by factors such as infections or adverse reactions to medications.

Myasthenia gravis can develop at any age. For reasons not fully understood, it's most frequently diagnosed in women under 40 and men over 60. It's rare in children, but some infants born to mothers with myasthenia gravis exhibit signs and symptoms of the condition for a short period after birth. This temporary occurrence is called transient neonatal myasthenia gravis.

Inheritance:

In the majority of cases, myasthenia gravis is not inherited and occurs spontaneously in individuals without a family history of the condition. Approximately 3 to 5 percent of affected individuals have family members with myasthenia gravis or other autoimmune diseases, but the specific pattern of inheritance is currently unknown.