Metabolic Diseases of muscles
Metabolic Diseases of the Muscles comprise of a number of Glycogen Storage Diseases and Mitochondrial Myopaties.
Glycogen Storage Diseases
Glycogen storage diseases (GSDs) are a group of inherited genetic disorders that cause glycogen to be improperly formed or released in the body. They are characterized by the accumulation of abnormal amounts or types of glycogen in tissues.
Glucose is a simple sugar, which is a form of carbohydrate. It is found in many foods and is the main source of energy for our bodies. Glycogen is the storage form of glucose in our bodies. Glycogen storage diseases are due to either a deficiency or blockage of an enzyme that is important in converting glucose to glycogen so it can be stored in the body for later use. The main places glycogen is stored in the body includes the liver and muscle cells.
The main types of GSDs are categorized by number and name. They include:
- Type I – Von Gierke disease, defect in glucose-6-phosphatase, this is the most common type of GSD, and accounts for 90% of all GSD cases
- Type II – Pompe’s disease (Acid Maltase Deficiency)
- Type III – Cori’s or Forbe’s disease/debrancher enzyme deficiency
- Type IV – Andersen’s disease/brancher enzyme deficiency
- Type V – McArdle’s disease/muscle glycogen phosphorylase deficiency
- Type VI – Hers’ disease/liver phosphorylase deficiency
- Type VII – Tarui’s disease/muscle phosphofructokinase deficiency
- Type IX – liver glycogen phosphorylase kinase deficiency
Mitochondrial myopathies
Just as some diseases are named for the part of the body they affect (like heart disease), mitochondrial diseases are so named because they affect a specific part of the cells in the body. Specifically, mitochondrial diseases affect the mitochondria – tiny energy factories found inside almost all our cells.
A mitochondrial disease that causes prominent muscular problems is called a mitochondrial myopathy (myo means muscle, and pathos means disease), while a mitochondrial disease that causes both prominent muscular and neurological problems is called a mitochondrial encephalomyopathy (encephalo refers to the brain).
Sourced from https://www.mda.org/disease/mitochondrial-myopathies accessed 31 March 2016.
MELAS – mitochondrial encephalomyopathy, lactic acidosis and stroke-like episodes
MERRF – myoclonus epilepsy with ragged red fibers
MIDD – maternally inherited diabetes and deafness
NARP – neuropathy, ataxia and retinitis pigmentosa
Useful Links:
Medsafe Data on medicines to avoid in mitochondrial diseases:
http://www.medsafe.govt.nz/profs/PUArticles/June2017/MitochondrialDisordersMedicinestoAvoid.htm