Myopathies related to glycogen metabolism panel [21 genes]
Metabolic myopathies are a group of secondary hereditary muscle diseases of enzymatic defects that affect the metabolic process and production of muscle energy. Some of them are considered to be inborn errors of metabolism and, even though they are rare causes of myopathy, their diagnostic importance lies in that some of them are potentially treatable.
Symptomatology may be similar to other forms of muscular dystrophy or inflammatory myopathies, usually with subtle symptoms, such as asymptomatic elevation of CPK, muscle cramps, myalgia, or myoglobinuria. Their prevalence is unknown: Pompe disease (acid maltase deficiency) affects 1 in 40,000 and McArdle disease 1 in 100,000 individuals.
Their etiology is related to problems in the metabolism of glycogen, lipids, or mitochondrial oxidation. Because of this, we have designed three specific panels for each metabolic pathway and a comprehensive panel that contemplates all of the implicated genes as a whole.
Priority Genes : Genes where there is sufficient evidence (clinical and functional) to consider them associated with the disease; they are included in the clinical practice guidelines.
Secondary Genes: Genes related to the disease, but with a lower level of evidence or that constitute sporadic cases.
* Candidate Genes: Not enough evidence in humans, but potentially associated with the disease.
- GAA: Pompe disease (Glycogenosis type II)
- PYGM: McArdle disease (Glycogenosis type V)
- LAMP2: Danon disease
- PFKM: Muscle phosphofructokinase deficiency (Glycogenosis type VII)
- GYG1 / RBCK1: Myopathy due to polyglucosan bodies
- AGL / GBE1: Deficiency of glycogen branching/debranching enzyme
- PGAM2: Phosphoglycerate mutase deficiency (Glycogenosis type X)
- PGK1: Phosphoglycerate kinase deficiency
- PGM1: Glycosylation congenital disorder type I
- PHKA1 / PHKA2 / PHKB / PHKG2: Phosphorylase kinase deficiency (Glycogenosis type IX)
- LDHA: Lactate dehydrogenase deficiency (Glycogenosis type XI)
- ENO3: Enolase deficiency type III
- Berardo A, DiMauro S, Hirano M. A diagnostic algorithm for metabolic myopathies. Curr Neurol Neurosci Rep 2010; 10:118-26.
- Darras BT, Friedman NR. Metabolic myopathies: a clinical approach; part I. Pediatr Neurol 2000; 22:87-97.
- van Adel BA, Tarnopolsky MA. Metabolic myopathies: update 2009. J Clin Neuromuscul Dis 2009; 10:97-121.