In: Biology
Glutamine Synthetase Deficiency, is an extremely rare disorder.
Describe the issue that would occur in the amino acid pathways if a
patient had the disorder, also why might it be under
reported?
Glutamine Synthetase Disorder is an extremely rare recessive disorder causing brain malformation, multi-organ failure, and neonatal death because of diminished Glutamine Synthetase expression or a secondary deficiency of Glutamine Synthetase in the body.
Glutamine Synthetase (GS) is a cytosolic enzyme that produces the most abundant amino acid in the human body, Glutamine. High GS activity is seen in the human liver, brain, and muscle. It catalyzes the condensation of glutamate and ammonia to form glutamine:
Glutamate + ATP + ammonia → Glutamine + ADP + phosphate
Glutamine synthetase plays an important role in regulating the concentrations of ammonia and glutamate in brain tissues by converting these potentially neurotoxic metabolites to glutamine by ammonia detoxification and inter-organ nitrogen flux.
Glutamine is a major substrate for various metabolic pathways in the body, and its' absence opposes the normal functioning of the body.
So far, GS deficiency has been diagnosed in only 3, unrelated patients, all of them showing decreased levels of glutamine in bodily fluids like serum, urine, and cerebrospinal fluid, associated with chronic hyperammonemia (increased levels of ammonia). Each of the patients had a homozygous mutation in the glutamine synthetase gene and that led to severely reduced GS activity.
This disorder might be under-reported because decreased concentrations of certain metabolites, like Glutamine in plasma and urine, do not receive as much attention as increased levels.