SNP Shot: Genomic Insights

Cap myopathy is a condition mainly impacting skeletal muscles, responsible for body movement. Individuals with this myopathy experience muscle weakness and reduced muscle tone throughout their body. However, the face, neck, and limbs are most significantly affected. This muscle weakness, present from birth or childhood, can progressively worsen.

Infants with cap myopathy might struggle with feeding and swallowing. Delays in achieving motor milestones, such as sitting, crawling, standing, and walking, are common. Affected individuals may experience frequent falls, fatigue easily, and find running, stair climbing, or jumping difficult. Breathing muscles can also be affected in some cases, leading to potentially life-threatening respiratory problems.

Physical characteristics of cap myopathy can include a high-arched palate, pronounced drooping eyelids (ptosis), and an elongated facial appearance. Some individuals may develop an exaggerated lower back curve (lordosis) or a sideways curvature of the spine (scoliosis).

The term "cap myopathy" originates from distinctive cap-shaped structures observable within muscle cells under a microscope. The severity of the condition correlates with the proportion of muscle cells displaying these caps. Individuals with 70-75% of their muscle cells showing caps typically face severe respiratory issues and may not survive past childhood. Conversely, those with only 10-30% of muscle cells affected tend to experience milder symptoms and can live into adulthood.

Inheritance:

Cap myopathy is an autosomal dominant disorder. This means that possessing just one copy of the mutated gene in each cell is enough to cause the condition. In most instances, the condition is not inherited but arises from new gene mutations. These cases occur in individuals without any prior family history of cap myopathy.