Hi,
Thanks for writing in.
Metabolic myopathies are a group of heriditary muscle disorders caused by enzymatic defects due to defective gene. Most of the disorders although rare are treatable. They can be of three types like glycogen storage diseases, lipid storage diseases and disorders of purine nucleotide metabolism and mitochondrial disorders.
CPK levels are elevated in most myopathies. Other valuable test is needle EMG.
http://www.emedicine.com/neuro/TOPIC672.HTM
This link has some useful information related to myopathies. Please consult an experienced neurologist and keep us posted.
my duaghter is hypotonic, she is 1 year and 9 months old and still can't walk or stand up, she is subjected to physical therapy, it helps but it needs time, you have to be patient and don't miss any physotherapy session. my daughter has a normal CPK result but has a problem in her nerve system which was diagnosed a month ago. try to do all medical tests required like MRI, muscle scanning, nerve scanning, amino acid, organic acids, ammonia, lactate, repeat the CPK test since it may get better with time, blood gases, hormones, immunology system test (blood viruses), don't forget to examine her vision it might be weak since most children with hypotonia have weak vision. good luck and may God help you and heal your daughter