Age criteria for JRA –
The general rule in that :


Myopathies have proximal muscle weakness.


Neuropathies have distal muscle weakness.


Myotonic dystrophy is an exception to this general rule and mainly involves the distal muscles. Also know
The difference between myopathy and muscular dystrophy.
Myopathy


Any skeletal muscle disorder that causes structural changes or functional impairment of muscle. It also includes muscular dystrophies.

Muscular dystrophy

The muscular dystrophy means abnormal growth of muscle.
It is characterized by -


It is a primary myopathy iii) Course is progressive
It has genetic basis           iv) Degeneration & Death of muscle fibers occur at some stage of the disease


So, muscular dystrophy is a type of myopathy.
< 10 years
< 12 years
< 14 years
< 16 years