=== Investigations ===
The serum [[creatinine]] is raised.
=== Differential diagnosis ===
*[[Acid maltase deficiency]]
*[[Danon disease]]=== Diagnosis ===
The diagnosis can be established by muscle biopsy.
== Genetics ==
This disorder is inherited in a recessive X linked fashion. As a result males are much more commonly affected than females.
It is due to a mutation in [[VMA21]] gene - the human [[homolog]] of the [[yeast]] Vma21p protein. This gene is located on the long arm of [[chromosome X]] (Xq28). It is a is an essential assembly of the vacuolar [[ATPase]] - the principal mammalian proton pump complex. Mutations in this gene increase lysosomal pH. This in turn reduces lysosomal degradative ability and blocks [[autophagy]].