GA1 Fact File

Prevalence  1:109,191 (EU data)
Defect type Autosomal recessive condition caused by a
deficiency of the enzyme glutaryl-CoA dehydrogenase (GCDH).
Typical age at clinical diagnosis 5 months – 6 years (UK data)


Clinical Effects:

  • Without treatment, many patients will sustain injury to the brain, usually around 9 months of age
  • Minor illnesses, such as a tummy upset or chest infection, cause the body to break down protein. In patients with GA1, this causes a build-up of harmful chemicals. These chemicals affect the brain, causing vomiting, irritability, drowsiness and coma.
  • Unfortunately, after a coma, most patients have permanent brain damage.
  • The brain injury causes problems with movement called dystonia and dyskinesia.  In dystonia, the brain causes the musles of the body to contract continuously causing an abnormal posture. Dyskinesia is a condition where involuntary jerky or writhing movements  occur.
  • The dystonia and dyskinesia can cause problems relating to mobility, feeding and breathing.
  • Some people with GA1 also have fits (seizures).
  • The brain injury has relatively little effect on the child’s intelligence, but communication can be very difficult.
  • If untreated, unfortunately many patients die in early adulthood.  Screening allows early treatment to begin.


It is important to make an early diagnosis and begin treatment before brain damage has occurred.   Treatment involves a low-protein, lysine-restricted diet along with a medicine (carnitine).

An emergency regimen is used when the patient has an illness to prevent a metabolic crisis. This emergency regimen involves giving glucose (sugar) either by mouth (at home) or into the veins (in hospital).

What is lysine?

Proteins in foods are made of smaller building blocks called amino acids.  Lysine is an amino acid in protein which people with GA1 are unable to break down.  Diets need to be low in lysine to prevent the patient becoming ill.  

Effectiveness of treatment:

This treatment can usually prevent brain damage in GA1. Unfortunately, if brain damage has already occurred, nothing can reverse this. The risk of a brain injury (and the need for a special diet) is much lower after early childhood. Expert guidelines on the management of GA1 were published in 2007.      


Positive predictive value 42% (Mean EU data – see PHG
Sensitivity Approx 100%
Screening index metabolite Glutaryl carnitine, C5DC
Confirmatory test Plasma acylcarnitines, urinary organic acids, 3-OH glutarate, urinary glutaryl carnitine