Glycogen storage disease type IX is a

hereditary Heredity, also called inheritance or biological inheritance, is the passing on of traits from parents to their offspring; either through asexual reproduction or sexual reproduction, the offspring cells or organisms acquire the genetic infor ...

deficiency of glycogen

phosphorylase kinase Phosphorylase kinase (PhK) is a serine/threonine-specific protein kinase which activates glycogen phosphorylase to release glucose-1-phosphate from glycogen. PhK phosphorylates glycogen phosphorylase at two serine residues, triggering a conformatio ...

B that affects the

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 ...

and

skeletal muscle Skeletal muscles (commonly referred to as muscles) are organs of the vertebrate muscular system and typically are attached by tendons to bones of a skeleton. The muscle cells of skeletal muscles are much longer than in the other types of m ...

tissue. It is inherited in an X-linked or

autosomal recessive In genetics, dominance is the phenomenon of one variant (allele) of a gene on a chromosome masking or overriding the effect of a different variant of the same gene on the other copy of the chromosome. The first variant is termed dominant and ...

manner. update 2011

Signs and symptoms

The signs and symptoms in glycogen storage disease type IX include: * Enlarged liver * Slowed growth * Motor development delay (mild) * Low blood sugar accompanied by ketosis * Lack of muscle tone Most of these signs and symptoms diminish as adulthood sets in.

Genetics

Glycogen storage disease type IX can be inherited via: *

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 ...

inheritance due to mutations at either

PHKA1 Phosphorylase b kinase regulatory subunit alpha, skeletal muscle isoform is an enzyme that in humans is encoded by the ''PHKA1'' gene. It is the muscle isoform of Phosphorylase kinase (PhK). The PHKA1 gene encodes the alpha subunit of muscle p ...

or the

PHKA2 Phosphorylase b kinase regulatory subunit alpha, liver isoform is an enzyme that in humans is encoded by the ''PHKA2'' gene In biology, the word gene (from , ; "... Wilhelm Johannsen coined the word gene to describe the Mendelian units of ...

(most common)

gene In biology, the word gene (from , ; "... Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a b ...

Autosomal recessive In genetics, dominance is the phenomenon of one variant (allele) of a gene on a chromosome masking or overriding the effect of a different variant of the same gene on the other copy of the chromosome. The first variant is termed dominant and ...

could be the inheritance pattern for an affected individual when the genes

PHKB Phosphorylase b kinase regulatory subunit beta is an enzyme that in humans is encoded by the ''PHKB'' gene In biology, the word gene (from , ; "... Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." mean ...

PHKG2 Phosphorylase b kinase gamma catalytic chain, testis/liver isoform is an enzyme that in humans is encoded by the ''PHKG2'' gene. The PHKG2 gene provides instructions for making one piece, the gamma subunit, of the phosphorylase b kinase enzyme. ...

have a

mutation In biology, a mutation is an alteration in the nucleic acid sequence of the genome of an organism, virus, or extrachromosomal DNA. Viral genomes contain either DNA or RNA. Mutations result from errors during DNA or viral replication, m ...

Diagnosis

The diagnosis of glycogen storage disease IX consists of the following: *

Complete blood count A complete blood count (CBC), also known as a full blood count (FBC), is a set of medical laboratory tests that provide information about the cells in a person's blood. The CBC indicates the counts of white blood cells, red blood cells and ...

Urinalysis Urinalysis, a portmanteau of the words ''urine'' and ''analysis'', is a panel of medical tests that includes physical (macroscopic) examination of the urine, chemical evaluation using urine test strips, and microscopic examination. Macroscopic ...

Histological Histology, also known as microscopic anatomy or microanatomy, is the branch of biology which studies the microscopic anatomy of biological tissues. Histology is the microscopic counterpart to gross anatomy, which looks at larger structures vis ...

study of the liver (via biopsy) *

Genetic testing Genetic testing, also known as DNA testing, is used to identify changes in DNA sequence or chromosome structure. Genetic testing can also include measuring the results of genetic changes, such as RNA analysis as an output of gene expression, or ...

* Physical exam

Types

There are two types of this inherited condition, ''glycogen storage disease IXa1'' and ''glycogen storage disease IXa2'' that affect the liver of an individual. Mutations in

have been seen in individuals with glycogen storage disease IXa2.

Management

The management of Glycogen storage disease IX requires treatment of symptoms by frequent intake of complex carbohydrates and protein to combat the low blood sugar. A nutritionist will advise on suitable diets. Liver function is regularly monitored and problems managed as they arise. However, liver problems have only been successfully treated by a

transplant Transplant or Transplantation may refer to: Sciences *Transplanting a plant from one location to another *Organ transplantation, moving an organ from one body to another *Transplant thought experiment, an experiment similar to Trolley problem *Tra ...

. Routine checks of metabolism are needed to ensure blood sugar (glucose) and ketones are managed. Regular moderate exercise is beneficial, although over-vigorous exercise is to be avoided, especially in those with enlarged livers.

References

External links

* {{Carbohydrate metabolic pathology Genetic diseases and disorders