Myopathy/Dystophy/Atrophy

Question 1

What is myotonic dystrophy?

Answer 1

It is an autosomal dominant condition characterised by muscle weakness and wasting.

Those with the disease have prolonged muscle contractions (myotonia) and are not able to relax certain muscles after use. (Unable to ungrip there hand)

Usually affects individuals in 20-50’s onset of the disease becomes earlier in each generation.

Other symptoms include:

• cataracts
• developmental delay and mild learning difficulty
• balding and development of infertility
• cardiomyopathy

Question 2

What is spinal muscular atrophy?

Answer 2

It is an autosomal recessive condition causing:

• degeneration of the anterior horn cells
• leading to progressive weakness and wasting of skeletal muscles

There are 3 different types:
SMA 1/2/3

Type 1: most severe, children never sit unaided die of respiratory failure within 12 months

Type 2: Children will sit but never walk

Type 3: Children will walk but will present with symptoms later in life

Question 3

What is Duchenne’s Muscular Dystrophy?

Answer 3

It is an x-linked recessive disorder, although about a third have new mutations.

Characterised by muscle weakness and motor delay.

Its is often diagnosed between the ages of 3 -7 due to a gross motor delay and the demonstration of Gower’s sign.

Question 4

What are congenital muscular dystrophies?

Answer 4

A group of autosomal recessive conditions in which there is weakness, hypotonia and contractures in certain limbs.

Weakness tends to be proximal.

Unlike DMD these present from birth they also have slightly longer and more variable life expectancies