A glycogen storage disease (GSD, also glycogenosis and dextrinosis) is a
metabolic disorder
A metabolic disorder is a disorder that negatively alters the body's processing and distribution of macronutrients, such as proteins, fats, and carbohydrates. Metabolic disorders can happen when abnormal chemical reactions in the body alter t ...
caused by an
enzyme
Enzymes () are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrates, and the enzyme converts the substrates into different molecules known as products ...
liver
The liver is a major organ only found in vertebrates which performs many essential biological functions such as detoxification of the organism, and the synthesis of proteins and biochemicals necessary for digestion and growth. In humans, it ...
cells.
GSD has two classes of cause: genetic and acquired. Genetic GSD is caused by any
inborn error of metabolism
Inborn errors of metabolism form a large class of genetic diseases involving congenital disorders of enzyme activities. The majority are due to defects of single genes that code for enzymes that facilitate conversion of various substances ( substr ...
(genetically defective
enzyme
Enzymes () are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrates, and the enzyme converts the substrates into different molecules known as products ...
s) involved in these processes. In livestock, acquired GSD is caused by
intoxication
Intoxication — or poisoning, especially by an alcoholic or narcotic substance — may refer to:
* Substance intoxication:
** Alcohol intoxication
** LSD intoxication
** Toxidrome
** Tobacco intoxication
** Cannabis intoxication
** Cocaine i ...
with the
alkaloid
Alkaloids are a class of basic, naturally occurring organic compounds that contain at least one nitrogen atom. This group also includes some related compounds with neutral and even weakly acidic properties. Some synthetic compounds of similar ...
castanospermine
Castanospermine is an indolizidine alkaloid first isolated from the seeds of ''Castanospermum australe''. It is a potent inhibitor of some glucosidase enzymes and has antiviral activity ''in vitro'' and in mouse models.
The castanospermine deri ...
.
Types
Remarks:
* Some GSDs have different forms, e.g. infantile, juvenile, adult (late-onset).
* Some GSDs have different subtypes, e.g. GSD1a / GSD1b, GSD9A1 / GSD9A2 / GSD9B / GSD9C / GSD9D.
* GSD type 0: Although
glycogen synthase
Glycogen synthase (UDP-glucose-glycogen glucosyltransferase) is a key enzyme in glycogenesis, the conversion of glucose into glycogen. It is a glycosyltransferase () that catalyses the reaction of UDP-glucose and (1,4--D-glucosyl)n to yield UD ...
deficiency does not result in storage of extra glycogen in the liver, it is often classified with the GSDs as type 0 because it is another defect of glycogen storage and can cause similar problems.
* GSD type VIII (GSD 8): In the past it was considered a distinct condition, however it is now classified with GSD type VI or GSD IXa1; it has been described as
X-linked recessive
X-linked recessive inheritance is a mode of inheritance in which a mutation in a gene on the X chromosome causes the phenotype to be always expressed in males (who are necessarily homozygous for the gene mutation because they have one X and one Y ...
inherited.Definition: glycogen storage disease type VIII from Online Medical Dictionary
* GSD type XI (GSD 11): Fanconi-Bickel syndrome, hepatorenal glycogenosis with renal Fanconi syndrome, no longer considered a glycogen storage disease.
* GSD type XIV (GSD 14): Now classed as
Congenital disorder of glycosylation
A congenital disorder of glycosylation (previously called carbohydrate-deficient glycoprotein syndrome) is one of several rare inborn errors of metabolism in which glycosylation of a variety of tissue proteins and/or lipids is deficient or defect ...
type 1 (CDG1T), affects the phosphoglucomutase enzyme (gene PGM1).
*
Lafora disease
Lafora disease is a rare, adult-onset and autosomal recessive genetic disorder which results in Myoclonus#Epilepsy forms, myoclonus epilepsy and usually results in death several years after the onset of symptoms. The disease is characterized by t ...
is considered a complex neurodegenerative disease and also a glycogen metabolism disorder.
* Polyglucosan Storage Myopathies are associated with defective glycogen metabolism
* (Not McArdle Disease) AMP-independent myophosphorylase deficiency: Autosomal dominant mutation on PYGM gene. AMP-independent myophosphorylase activity impaired, whereas the AMP-dependent activity was preserved. No exercise intolerance. Adult-onset muscle weakness. Accumulation of the intermediate filament desmin in the myofibers of the patients.
* Unknown glycogenosis related to dystrophy gene deletion: patient has a previously undescribed myopathy associated with both Becker muscular dystrophy and a glycogen storage disorder of unknown aetiology.
Diagnosis
Treatment
Treatment is dependent on the type of glycogen storage disease. GSD I is typically treated with frequent small meals of carbohydrates and
cornstarch
Corn starch, maize starch, or cornflour (British English) is the starch derived from corn (maize) grain. The starch is obtained from the endosperm of the kernel. Corn starch is a common food ingredient, often used to thicken sauces or so ...
allopurinol
Allopurinol is a medication used to decrease high blood uric acid levels. It is specifically used to prevent gout, prevent specific types of kidney stones and for the high uric acid levels that can occur with chemotherapy. It is taken by mouth ...
British Columbia
British Columbia (commonly abbreviated as BC) is the westernmost province of Canada, situated between the Pacific Ocean and the Rocky Mountains. It has a diverse geography, with rugged landscapes that include rocky coastlines, sandy beaches, ...
, approximately 2.3 children per 100,000 births (1 in 43,000) have some form of glycogen storage disease. In the United States, they are estimated to occur in 1 per 20,000–25,000 births.eMedicine Specialties > Glycogen-Storage Disease Type I Author: Karl S Roth. Updated: Aug 31, 2009 Dutch incidence rate is estimated to be 1 per 40,000 births.
While a Mexican incidence showed 6.78:1000 male newborns.
IamGSD - International Association for Muscle Glycogen Storage Disease. A non-profit, patient-led international group encouraging efforts by research and medical professionals, national support groups and individual patients worldwide.
IPA - International Pompe Association. (Pompe Disease is also known as GSD-II). A non-profit, federation of Pompe disease patient's groups world-wide. It seeks to coordinate activities and share experience and knowledge between different groups.
EUROMAC - EUROMAC is a European registry of patients affected by McArdle Disease and other rare neuromuscular glycogenoses.
CoRDS - Coordination of Rare Diseases at Sanford (CoRDS) is a centralized international patient registry for all rare diseases. They work with patient advocacy groups, including IamGSD, individuals and researchers.
CORD - Canadian Organization for Rare Disorders (CORD) is a Canadian national network for organizations representing all those with rare disorders. CORD provides a strong common voice to advocate for health policy and a healthcare system that works for those with rare disorders.
NORD - National Organization for Rare Disorders (NORD) is an American national non-profit patient advocacy organization that is dedicated to individuals with rare diseases and the organizations that serve them.
EURODIS - Rare Diseases Europe (EURODIS) is a unique, non-profit alliance of over 700 rare disease patient organizations across Europe that work together to improve the lives of the 30 million people living with a rare disease in Europe.
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Inborn errors of carbohydrate metabolismHepatologyRare diseasesDiseases of liver