- Fructose bisphosphatase deficiency
Name = PAGENAME
Width = 175px
DiseasesDB = 5012
ICD10 = ICD10|E|74|1|e|70
OMIM = 229700
eMedicineSubj = ped
eMedicineTopic = 806
MeshID = D015319
In Fructose bisphosphatase deficiency, there is not enough
fructose bisphosphatasefor gluconeogenesisto occur correctly. Glycolysis(the break-down of glucose) will still work, as it does not use this enzyme.
Without effective gluconeogenesis (GNG),
hypoglycaemiawill set in after about 12 hours. This is the time when liver glycogenstores have been exhausted, and the body has to rely on GNG. When given a dose of glucagon(which would normally increase blood glucose) nothing will happen, as stores are depleted and GNG doesn't work. (In fact, the patient would already have high glucagon levels.)
There is no problem with the metabolism of glucose or galactose, but
fructoseand glycerolcannot be used as fuels. If fructose or glycerol are given, there will be a build up of phosphorylated three-carbon sugars. This leads to phosphate depletion within the cells, and also in the blood. Without phosphate, ATP cannot be made, and many cell processes cannot occur.
High levels of glucagon will tend to release
fatty acids from adipose tissue, and this will combine with glycerolthat cannot be used in the liver, to make triacylglycerides causing a fatty liver.
As three carbon molecules cannot be used to make glucose, they will instead be made into
pyruvateand lactate. These acids cause a drop in the pHof the blood (a metabolic acidosis). Acetyl CoA(acetyl co-enzyme A) will also build up, leading to the creation of ketone bodies.
To treat people with a deficiency of this enzyme, they must avoid needing gluconeogenesis to make glucose. This can be accomplished by not fasting for long periods, and eating high-carbohydrate food. They should avoid fructose containing foods (as well as
sucrosewhich breaks down to fructose).
As with all single-gene metabolic disorders, there is always hope for genetic therapy, inserting a healthy copy of the gene into existing liver cells.
*cite book | first = Salvatore | last = diMauro | coauthors = Darryl C. De Vivo | year = 1998 | month = October | title = Basic Neurochemistry: Molecular, Cellular and Medical Aspects | chapter = Diseases of Carbohydrate, Fatty Acid and Mitochondrial Metabolism | editor = George J. Siegel et al (ed.) | edition = 6th Edition | publisher = Lippincott Williams and Wilkins | location = Philadelphia, Pennsylvania | id = ISBN 0-7817-1745-0 | url = http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Search&db=books&doptcmdl=GenBookHL&term=fructose+bisphosphatase+AND+bnchm%5Bbook%5D+AND+161340%5Buid%5D&rid=bnchm.section.2968#2971
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