Muscular dystrophies Flashcards
Muscular dystrophies (MD) are a group of inherited genetic conditions that gradually cause the muscle atrophy and weakness, leading to an increasing level of disability. Is this a muscular or nerve issue?
- muscle issue
There are lots of different types of muscular dystrophy. Of the following which is the most common?
1 - Duchennes muscular dystrophy
2 - Beckers muscular dystrophy
3 - Myotonic dystrophy
4 - Facioscapulohumeral muscular dystrophy
5 - Oculopharyngeal muscular dystrophy
6 - Limb-girdle muscular dystrophy
7 - Emery-Dreifuss muscular dystrophy
1 - Duchennes muscular dystrophy
Beckers muscular dystrophy is a less severe form of Duchennes muscular dystrophy, where there is some function of dystrophin
Duchennes muscular dystrophy is the most common type of muscular dystrophy. What is the inheritance pattern of Duchennes muscular dystrophy?
1 - autosomal dominant
2 - x-linked dominant
3 - autosomal recessive
4 - x-linked recessive
4 - x-linked recessive
X relates to the X chromosome
- if male has this they will be affected as they only have one X chromosome
- if female has this they will be carrier as they have 2 X chromosomes, they will need to mutated X chromosomes to be affected
What is the incidence of Duchennes muscular dystrophy?
1 - 150 cases per 100,000
2 - 15 cases per 100,000
3 - 1.5 cases per 100,000
4 - 0.15 cases per 100,000
4 - 0.15 cases per 100,000
Much more common in males due to X linked inheritance pattern
What age is the peak incidence of Duchennes muscular dystrophy?
1 - 1-5
2 - 5-15
3 - 20-30
4 - >30
1 - 1-5
- 5-15 years = Beckers
- > 30 years = lower limb girdle
What is typically affected in the mutation causing Duchennes muscular dystrophy?
1 - B-actin
2 - desmin
3 - dystrophin
4 - titin
3 - dystrophin
Dystrophin connects intracellular actin to the dystrophin associated protein complex (DAPC)
- DAPC attaches to the extracellular matrix.
Dystrophin essentially, acts as a stabiliser for the sarcolemma, without it the sarcolemma becomes damaged and weak
Do children with Duchennes muscular dystrophy begin to walk at the same age as healthy children?
- no
They are delayed and have a waddling gait and increased falls
Most motor signs are delayed in Duchennes muscular dystrophy
Children with Duchennes muscular dystrophy have a specific muscle group that undergoes pseudohypertrophy, which is really due to fat and fibrosis. Which muscle group is this?
1 - quadriceps
2 - hamstrings
3 - calves
4 - biceps
3 - calves
Children with Duchennes muscular dystrophy can have difficulty moving from a lying to standing position, where they go onto all fours, then into downward dog and push backwards. What is this sign called?
1 - trellenberg sign
2 - gowers sign
3 - babinski reflex
4 - hoffmans sign
2 - gowers sign
In Duchennes muscular dystrophy, their is muscle weakness. Is this distal to proximal or proximal to distal muscle weakness?
- proximal to distal muscle weakness
Children with duchennes muscular dystrophy can have an intellectual disability. What % of patient experience this?
1 - 3%
2 - 13%
3 - 30%
4 - 65%
3 - 30%
Which of the following is NOT a late symptom of duchennes muscular dystrophy?
1 - wheelchair bound/help
2 - gastrointestinal failure
3 - respiratory failure (weak diaphragm) 4 - scoliosis
5 - dilated cardiomyopathy and arrhythmias
6 - shortened lifespan.
2 - gastrointestinal failure
Genetic testing through western blot or DNA testing is the gold standard diagnosis. However, which of the following is almost always raised and gives a good indicator of duchennes muscular dystrophy?
1 - creatinine kinase (CK)
2 - lactate dehydrogenase (LDH)
3 - alanine aminotransferase (ALT)
4 - aspartate aminotransferase (AST)
1 - creatinine kinase (CK)
All others can also be raised
Duchennes muscular dystrophy cannot be cured. Which of the following can slow down muscle degeneration?
1 - zoledronic acid
2 - folic acid
3 - vitamin K
4 - glucocorticoids
4 - glucocorticoids
Prednisolone is drug of choice
BUT long term use can cause weight gain, osteoporosis and impaired glucose tolerance
Physical therapy can be helpful, but does not stop the process
Steroid use can slow the degeneration in Duchennes muscular dystrophy. However, long term use can make the patient almost dependent. Stopping the steroids ab ruptly can cause which of the following?
1 - cushing syndrome
2 - addisonian crisis
3 - myxedema
4 - all of the above
4 - all of the above