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⚀ 220.127.116.11 Introduction.
□ I thought it might be helpful out of general interest to go over a few of the major diseases. Most muscle diseases are linked to a genetic defect and are inherited. Therefore, most muscle diseases are seen at birth or in childhood. Genes produce proteins that are required to run things. Defective genes produce defective proteins. In some cases, the proteins are only partially defective, and in these cases, you end up with less severe cases of the disease. Altogether there are over 100 types of muscle diseases but only several major categories — there are many subtypes of several of these diseases. Almost all of these diseases are progressive. I'm going to start out with four major diseases that are often mentioned but are not muscle diseases per se.
□ Amyotrophic lateral sclerosis (ALS): affects cells in the brain/spinal cord that control voluntary muscle movement, speaking, swallowing, and breathing, cause unknown, no cure, adult-onset, rapid decline.
□ Multiple sclerosis (MS): deterioration of the insulation of nerves in the brain/spinal cord, a wide range of symptoms, cause unknown - autoimmune? no cure, adult-onset, two main types.
□ Parkinson's: brain cells stop making an important chemical (dopamine) that impacts control of movement and causes other problems as well, cause unknown, no cure, onset generally after 60.
□ Alzheimer's: cells in the brain that control thought, memory, and language breakdown causing dementia, cause unknown, no cure, onset generally after 60.
⚀ 18.104.22.168 Muscle Diseases.
□ Many diseases impact muscles, here are the major ones.
□ Duchenne (DMD): muscle weakness, genetic cause (abnormal protein), no cure, usually impacts males, from birth, maximum lifespan about 20.
□ Becker: same as Duchenne but much less severe, usually partial muscle function.
□ Myotonic: muscle weakness, after contraction muscles have difficulty relaxing, genetic cause (abnormal protein), no cure, mid to late adulthood, two major types.
□ Myasthenia gravis (MG): muscle weakness from damage in the junction between nerves and muscle, especially muscles that control the eyes, mouth, throat, and limbs, cause unknown, no cure, any age, but more frequently in women (age 20 and 30) and men over 50.
□ Charcot-Marie-Tooth disease (CMT): deterioration of the nerves in the arms and legs, impacts sensory information and muscle movement, genetic cause (abnormal proteins), no cure, any age, but more frequently late adolescence on, many different types.
□ Peripheral neuropathy: damage to the nerves in the arms and legs, often causes weakness, numbness, and pain, usually in the hands and feet (can also affect digestion, urination, and circulation), many different causes (most common: diabetes), no cure, many different types, onset variable.
□ Congenital: causes muscle weakness, fragile muscles, impacts muscle repair, genetic causes, no cure, present from birth, or in the first few months of life, many different types.
□ Limb-girdle (LGMD): muscle weakness around the hips and shoulders (limb-girdle muscles), genetic causes, no cure, present from birth, or in the first few months of life, two major types, many different sub-types.
□ Facioscapulohumeral (FSHD): muscle weakness in the face (facio-), around the shoulder blades (scapulo-), and in the upper arms (humeral-), genetic cause (abnormal proteins), no cure, usually appears in adolescence, variable in severity, two major types.
□ Oculopharyngeal (OPMD): causes muscle weakness of the eyes (oculo-) and throat (pharynx = pharyngeal), genetic cause (abnormal proteins), no cure, onset generally after 40.
□ Distal: muscle weakness that starts in the hands and feet, genetic cause (abnormal proteins), no cure, onset 40 - 60, many different types.
□ Emery-Dreifuss: muscle weakness impacting movement and the heart, genetic cause (abnormal proteins), no cure, onset generally after 40.
□ Inclusion body myopathy: Muscle weakness, genetic cause (abnormal proteins), no cure, onset generally after 20, several different types (early on looked like inclusion body myositis and the two conditions were lumped together, hence the very similar names).
⚀ 22.214.171.124 Idiopathic inflammatory “myopathies.”
□ Idiopathic inflammatory “myopathies” (IIMs) are a group of rare, acquired (not genetic — not inherited) disorders with primary features of muscle weakness and inflammation in the muscle. [[Example of confusing names — IIM are called myopathies but the main types are myositis conditions]]
□ Myositis: polymyositis (poly = many/widespread) - muscle weakness associated with inflammation, cause unknown - autoimmune? no cure, onset 30 and 60, more common in women (2:1), increased risk of cancer.
□ Myositis: dermatomyositis (dermato = skin) - muscle weakness associated with inflammation, and a skin rash, cause unknown - autoimmune? no cure, onset 30 and 60, more common in women (2:1), increased risk of cancer.
□ Myositis: Inclusion body myositis (Inclusion body = clumps seen under the microscope) - muscle weakness in the thighs (quadriceps), wrists, and fingers, associated with inflammation, often impacts swallowing, sometimes impacts breathing, cause unknown - autoimmune? onset after 40, no cure, more common in men (3:1) (not associated with cancer or heart).