Cap Myopathy

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MedlinePlus Genetics: ⁴² Cap myopathy is a disorder that primarily affects skeletal muscles, which are muscles that the body uses for movement. People with cap myopathy have muscle weakness (myopathy) and poor muscle tone (hypotonia) throughout the body, but they are most severely affected in the muscles of the face, neck, and limbs. The muscle weakness, which begins at birth or during childhood, can worsen over time.Affected individuals may have feeding and swallowing difficulties in infancy. They typically have delayed development of motor skills such as sitting, crawling, standing, and walking. They may fall frequently, tire easily, and have difficulty running, climbing stairs, or jumping. In some cases, the muscles used for breathing are affected, and life-threatening breathing difficulties can occur.People with cap myopathy may have a high arch in the roof of the mouth (high-arched palate), severely drooping eyelids (ptosis), and a long face. Some affected individuals develop an abnormally curved lower back (lordosis) or a spine that curves to the side (scoliosis).The name cap myopathy comes from characteristic abnormal cap-like structures that can be seen in muscle cells when muscle tissue is viewed under a microscope. The severity of cap myopathy is related to the percentage of muscle cells that have these caps. Individuals in whom 70 to 75 percent of muscle cells have caps typically have severe breathing problems and may not survive childhood, while those in whom 10 to 30 percent of muscle cells have caps have milder symptoms and can live into adulthood.

MalaCards based summary: Cap Myopathy, also known as cap disease, is related to myopathy and batten-turner congenital myopathy. An important gene associated with Cap Myopathy is TPM3 (Tropomyosin 3), and among its related pathways/superpathways are Cardiac conduction and Striated muscle contraction pathway. Affiliated tissues include prostate and skeletal muscle, and related phenotypes are high palate and reduced tendon reflexes

GARD: ¹⁹ Cap myopathy is a disorder that primarily affects skeletal muscles, the muscles that the body uses for movement. People with Cap myopathy have muscle weakness (myopathy) and poor muscle tone (hypotonia) throughout the body, but they are most severely affected in the muscles of the face, neck, and limbs. The name Cap myopathy comes from characteristic abnormal cap-like structures that can be seen in muscle cells when muscle tissue is viewed under a microscope. Individuals in whom 70 to 75 percent of muscle cells have caps typically have severe breathing problems and may not survive childhood, while those in whom 10 to 30 percent of muscle cells have caps have milder symptoms and can live into adulthood. Cap myopathy can be caused by genetic changes in the in the ACTA1, TPM2, or TPM3 genes. This condition follows an autosomal dominant manner of inheritance, however, most cases are not inherited; they result from new genetic changes in the gene and occur in people with no history of the disorder in their family.

Orphanet: ⁵⁸ Cap myopathy is a very rare congenital myopathy presenting a weakness of facial and respiratory muscles associated with craniofacial and thoracic deformities, as well as weakness of limb proximal and distal muscles. Onset is at birth or in childhood, weakness progression is slow but may lead to a severe and even fatal prognosis.

Search Clinical Trials, NIH Clinical Center for Cap Myopathy