Sandbox WWC3: Difference between revisions
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===Hypokalemic Periodic Paralysis=== | ===Hypokalemic Periodic Paralysis=== | ||
Hypokalemic periodic paralysis is caused by the mutations Arg669His, Arg672His, Arg672Gly, Arg672Ser, R1132Q, P1158S in the S4 segment of the NaV1.4 sodium channel. <ref name = "Hypo">http://neuromuscular.wustl.edu/mtime/mepisodic.html#hopp</ref>.It is a loss of function mutation resulting in attacks of muscular weakness <ref name = "Hypo"/>. This disorder is a dominant mutation<ref name = "Groome">DOI: 10.1093/brain/awu015</ref>. Factors that trigger these episodes include meals rich in carbohydrates, rest after exercise, early morning hours, and emotional stress <ref name = "Groome"/>. Most mutations are in two the Arg residues closes to the extracellular side of the S4 segment <ref name = "Groome"/>. These mutations cause a leak current of Na+ ions inward, which is called an "omega" current <ref name = "Groome"/>. This inward current causes the K+ channels to not be effective and results in muscle weakness <ref name = "Groome"/>. | Hypokalemic periodic paralysis is caused by the mutations Arg669His, Arg672His, Arg672Gly, Arg672Ser, R1132Q, P1158S in the S4 segment of the NaV1.4 sodium channel. <ref name = "Hypo">http://neuromuscular.wustl.edu/mtime/mepisodic.html#hopp</ref>.It is a loss of function mutation resulting in attacks of muscular weakness <ref name = "Hypo"/>. This disorder is a dominant mutation<ref name = "Groome">DOI: 10.1093/brain/awu015</ref>. Factors that trigger these episodes include meals rich in carbohydrates, rest after exercise, early morning hours, and emotional stress <ref name = "Groome"/>. Most mutations are in two the Arg residues closes to the extracellular side of the S4 segment <ref name = "Groome"/>. These mutations cause a leak current of Na+ ions inward, which is called an "omega" current <ref name = "Groome"/>. This inward current causes the K+ channels to not be effective and results in muscle weakness <ref name = "Groome"/>. | ||
===Myotonia Fluctuans=== | ===Myotonia Fluctuans=== | ||
Myotonia fluctuans is due to the G1306A mutation in the NaV1.4 sodium channel<ref name = "Fluct">http://neuromuscular.wustl.edu/mother/activity.html#mf</ref>. All mutations at the 1306 site cause reduced channel inactivation due to the fact that they are located on the hinge of the channel inactivation gate <ref name = "Fluct"/>. This disease is characterized by the inability to relax voluntary muscle after vigorous exercise. However, the condition fluctuates day to day, hence the name<ref name = "Fluct"/>. | |||
===Myotonia Permanens=== | ===Myotonia Permanens=== | ||
Myotonia permanens is similar to myotonia fluctuans in that it causes the inability to relax voluntary muscle<ref name = "Fluct"/>. However, this disease is caused by the Gly1306Glu mutation<ref name = "Fluct"/>. Again, this mutation causes reduced channel inactivation due to the location of the mutation on the inactivation gate <ref name = "Fluct"/>. Severe myotonia permanens may interfere with respiration and is worsened after eating K+ rich foods <ref name = "Fluct"/>. | |||
==References== | ==References== | ||
<references/> | <references/> | ||
