MUSCULAR DYSTROPHY/ GENETIC DISEASE-CAUSING DISTURBANCES IN CALCIUM HOMEOSTASIS

Question 1

Muscle wasting -progressive weakness

Answer 1

MUSCULAR DYSTROPHY

Question 2

 Severe muscle wasting and weakness (progressive)
 X-linked recessive disease linked to a defect in dystrophin gene
 Dystrophin protein is absent

Answer 2

1. Duchenne’s Muscular Dystrophy (DMD)

Question 3

It is the protein absent in Duchenne’s Muscular Dystrophy (DMD)

Answer 3

Dystrophin

Question 4

 Alteration of dystrophin gene or reduced amount of dystrophin gene
 Muscle wasting and weakness is less severe
 X-linked

Answer 4

2. Becker Muscle Dystrophy

Question 5

What is the difference of Becker Muscle Dystrophy to Duchenne’s Muscular Dystrophy (DMD)?

Answer 5

It is less severe and the dystrophin gene is reduced.

Question 6

 Defect in sarcolemma repair (attributed to loss/mutation of the protein dysferlin)
 Associated with muscle wasting in the pelvic region

Answer 6

3. Limb-Girdle Muscular Dystrophy 2B

Question 7

What causes Limb-Girdle Muscular Dystrophy 2B

Answer 7

It is due to the mutation of the protein dysferlin causing defect in sarcolemma repair

Question 8

Defect in the protein titin that have been implicated in other forms of muscular dystrophy

Answer 8

4. Limb-Girdle Muscular Dystrophy 2J

Question 9

• Autosomal dominant
• Skeletal muscle rigidity, tachycardia, hyperventilation, hyperthermia.
- due to excessive contraction which produces heat.
- due to abnormally in RYR which becomes activated by anesthesia agents.
• Usually a life-threatening consequence in certain surgical instances caused by anesthetic agents like haloethane and other muscle relaxants.

Answer 9

Malignant Hyperthermia

Question 10

• It is an autosomal dominant disorder.
• Leads to muscle weakness ( low energy in muscles )
• Loss of mitochondria in the core of the muscle fibers and some disintegration of the contractile filaments.
• Defect in RYR > increased intracellular Ca concentration > increased uptake of Ca by the mitochondria leading to overload and eventually loss of mitochondria

Answer 10

Central Core Disease:

Question 11

• Painless muscle cramping and impaired muscle relaxation during exercise in muscles of legs, arms and eyelids
• Caused due to reduced activity in SERCA.

Answer 11

Broody Disease

Question 12

• The muscle weakness that is caused in this type of disorder tends to become worse, when the affected muscle is in use.
• In this disorder, ones immune system starts making antibodies that tend to destroy the acetylcholine receptors in the muscle > there is reduced transmission of nerve signal into the muscle > muscle weakness.

Answer 12

Myasthenia Gravis:

Question 13

What causes Malignant Hyperthermia?

Answer 13

Due to abnormality in RYR that causes excessive contraction which produces heat.

Question 14

What causes Central Core Disease?

Answer 14

Due to loss of mitochondria in the core of the muscle fibers and some disintegration of the contractile filaments.

Question 15

What causes Broody Disease?

Answer 15

Due to reduced activity in SERCA

Question 16

What causes Myasthenia Gravis?

Answer 16

Due to antibodies attacking acetylcholine receptors in the muscle