What else is it called?
Hyperlysinaemia is also known as:
- Hyperlysinaemia type I
- Lysine alpha ketoglutarate reductase deficiency
- Lysine intolerance
- Alpha aminoadipic semialdehyde synthase deficiency
- L-lysine NAD-oxido-reductase deficiency
- Familial hyperlysinaemia
- Saccharopine dehydrogenase deficiency
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What causes it?
Hyperlysinaemia is caused by a problem in the gene that provides information for the production of the enzyme known as aminoadipic semialdehyde synthase (AASS) which is involved in the first two steps of lysine degradation. By having a problem in the gene that produces AASS you will be unable to breakdown lysine which causes a build-up of lysine in the blood and various amounts of saccharopinuria found in the blood and urine.
How common is it?
Unfortunately, the prevalence of hyperlysinaemia is unknown.
What are the signs and symptoms?
Hyperlysinaemia manifests itself during infancy and the signs and symptoms of hyperlysinaemia are:
- Growth inhibition
- High levels of lysine in the blood and cerebrospinal fluid
- Various levels of saccharopinuria
- Abnormality in the genitourinary system
- Cognitive impairment
- Delayed speech and language development
How is it diagnosed?
Hyperlysinaemia is a disease that can be diagnosed using newborn screening and genetic testing via the genetic testing registry, which will test for hyperlysinaemia and saccharopinuria.
Which can be tested by analyte, which is the any sample taken from the body such as blood, urine, saliva etc in the biochemical and genetics laboratory in the children’s hospital in Dayton, United States.
Can it be treated?
It is not yet proven but a low lysine or protein diet may be beneficial to some individuals.
Do my family need to be tested?
Every person has two genes that code for aminoadipic semialdehyde synthase. Since hyperlysinaemia is an autosomal recessive metabolic disorder, for a child to inherit it they will need to inherit two copies from their parents.
One from the mother which comes from the egg and the other from the father which comes from the sperm, which will produce the defective enzyme. The parents do not need to have hyperlysinaemia in order to pass it to their children in this case the father and mother are known as carriers, they have one defective gene and the normal functioning gene. Resulting in the parents not developing hyperlysinaemia.
When parents are both carriers of the hyperlysinaemia gene:
- There is a 25% chance that the child will be unaffected and not a carrier of the disease.
- There is a 25% chance that the child will be affected by hyperlysinaemia and carry both genes
- There is a 50% chance that they will produce children that are carriers of the disease and have only one hyperlysinaemia gene.