Myelin Sheath Disorder (MSD) This disorder is inherited as an autosomal dominant
ID: 15999 • Letter: M
Question
Myelin Sheath Disorder (MSD)
This disorder is inherited as an autosomal dominant trait. MSD is a neurodegenerative disease characterized mainly by myotonia (slow relaxation of the muscles after voluntary contraction, i.e. can’t set down a mug after picking it up), muscular degeneration, cataracts, diabetes, and ECG changes. Death may occur as a result of respiratory failure.
The MSD results from an amplified trinucleotide repeat, CAT, in the 3’ untranslated region (UTR) of MSDPK1 (myelin sheath disorder phosphokinase) mRNA. Normal individuals have 5 to 37 repeats, mildly affected persons have 50 to 150 repeats, patients with classic MSD have 100 to 1,000 repeats, and those with MSD at birth can have more than 2,000 repeats.
Q: What would be the sequence of the 3’ UTR of MSDPK1 mRNA if the sequence (5’CAT3’)8 is on the non-coding strand? Explain your reasoning.
Explanation / Answer
Myelin is a dielectric (electrically insulating) material that forms a layer, the myelin sheath, usually around only the axon of a neuron. It is essential for the proper functioning of the nervous system. Myelin is an outgrowth of a type of glial cell. The production of the myelin sheath is called myelination. In humans, the production of myelin begins in the fourteenth week of fetal development, although little myelin exists in the brain at the time of birth. During infancy, myelination occurs quickly and continues through the adolescent stages of life. Symptoms of myelin sheath degeneration depend on what part of the nerves have experienced demyelination. The most common symptoms include: Episodes of dizziness Loss of balance and coordination Increased reflexes Eye problems such as blurred or double vision Feelings of tingling or numbness, especially in the extremities Extreme fatigue Loss of arm, hand or leg strength Difficulty speaking and slurred speech Muscle tremors Muscle stiffness Paralysis Problems with thinking, concentration, memory and judgment go through this link http://www.evenbetterhealth.com/multiple-sclerosis.php
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