Myoneurogenic gastrointestinal encephalopathy
Encyclopedia
Mitochondrial neurogastrointestinal encephalopathy syndrome (MNGIE), also called myoneurogastrointestinal encephalopathy syndrome or POLIP syndrome, is a rare autosomal
recessive mitochondrial disease
usually appearing between the second and fifth decades of life. Unlike typical mitochondrial diseases caused by mitochondrial DNA
(mtDNA) mutations, MNGIE is caused by mutations in the TYMP
gene, which encodes the enzyme
thymidine phosphorylase. A secondary form of MNGIE, called MNGIE without leukoencephalopathy, can be caused by mutations in the POLG
gene.
) of the gastrointestinal tract become inefficient causing malabsorption . Borborygmi (stomach rumbling), early satiety, diarrhea, constipation, gastroparesis
, nausea, vomiting, weight loss, diverticulitis
. Neurological symptoms may include diffuse leukoencephalopathy
, peripheral neuropathy, and myopathy
.Ocular symptoms may include retinal degeneration, ophthalmoplegia (paralysis of eye muscles), ptosis
(drooping eyelids). Those with MNGIE are often thin, experiencing continuous weight loss.
Autosome
An autosome is a chromosome that is not a sex chromosome, or allosome; that is to say, there is an equal number of copies of the chromosome in males and females. For example, in humans, there are 22 pairs of autosomes. In addition to autosomes, there are sex chromosomes, to be specific: X and Y...
recessive mitochondrial disease
Mitochondrial disease
Mitochondrial diseases are a group of disorders caused by dysfunctional mitochondria, the organelles that are the "powerhouses" of the cell. Mitochondria are found in every cell of the human body except red blood cells...
usually appearing between the second and fifth decades of life. Unlike typical mitochondrial diseases caused by mitochondrial DNA
DNA
Deoxyribonucleic acid is a nucleic acid that contains the genetic instructions used in the development and functioning of all known living organisms . The DNA segments that carry this genetic information are called genes, but other DNA sequences have structural purposes, or are involved in...
(mtDNA) mutations, MNGIE is caused by mutations in the TYMP
ECGF1
Thymidine phosphorylase is an enzyme that in humans is encoded by the TYMP gene.-External links:* -Further reading:...
gene, which encodes the enzyme
Enzyme
Enzymes are proteins that catalyze chemical reactions. In enzymatic reactions, the molecules at the beginning of the process, called substrates, are converted into different molecules, called products. Almost all chemical reactions in a biological cell need enzymes in order to occur at rates...
thymidine phosphorylase. A secondary form of MNGIE, called MNGIE without leukoencephalopathy, can be caused by mutations in the POLG
POLG
DNA polymerase subunit gamma is an enzyme that in humans is encoded by the POLG gene.-Functions:POLG is the gene that codes for the catalytic subunit of the mitochondrial DNA polymerase, called DNA polymerase gamma . The human POLG cDNA and gene were originally cloned mapped to chromosome 15,...
gene.
Signs and symptoms
MNGIE is a multisystem disorder. Gastrointestinal symptoms may include gastrointestinal dysmotility possibly resulting in pseudo-obstruction in which the muscular contractions (peristalsisPeristalsis
Peristalsis is a radially symmetrical contraction and relaxation of muscles which propagates in a wave down the muscular tube, in an anterograde fashion. In humans, peristalsis is found in the contraction of smooth muscles to propel contents through the digestive tract. Earthworms use a similar...
) of the gastrointestinal tract become inefficient causing malabsorption . Borborygmi (stomach rumbling), early satiety, diarrhea, constipation, gastroparesis
Gastroparesis
Gastroparesis, also called delayed gastric emptying, is a medical condition consisting of a paresis of the stomach, resulting in food remaining in the stomach for a longer period of time than normal. Normally, the stomach contracts to move food down into the small intestine for digestion. The...
, nausea, vomiting, weight loss, diverticulitis
Diverticulitis
Diverticulitis is a common digestive disease particularly found in the large intestine. Diverticulitis develops from diverticulosis, which involves the formation of pouches on the outside of the colon...
. Neurological symptoms may include diffuse leukoencephalopathy
Leukoencephalopathy
The term Leukoencephalopathy is a broad term for leukodystrophy-like diseases . It is applied to all brain white matter diseases, whether their molecular cause is known or not...
, peripheral neuropathy, and myopathy
Myopathy
In medicine, a myopathy is a muscular disease in which the muscle fibers do not function for any one of many reasons, resulting in muscular weakness. "Myopathy" simply means muscle disease...
.Ocular symptoms may include retinal degeneration, ophthalmoplegia (paralysis of eye muscles), ptosis
Ptosis
Ptosis refers to droopiness of a body part. Specifically, it can refer to:* Ptosis * Ptosis * Enteroptosis * Gastroptosis...
(drooping eyelids). Those with MNGIE are often thin, experiencing continuous weight loss.