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IVA Fact File


Prevalence 1:155,000 (EU data – see PHG report)
Defect type Deficiency of isovaleryl-CoA dehydrogenase involved in the breakdown of the amino acid, leucine. It is an autosomal recessive disorder.
Typical age at clinical diagnosis 1 week - 5 years (UK data)

 

Clinical Effects:

  • IVA is a variable condition which can affect different people differently and at different stages in development.
  • Some patients with IVA become unwell within a few days of birth.
  • These babies develop sickness (vomiting), excessive sleepiness, floppiness or rapid breathing. Without treatment, this can lead to a coma.
  • Other children with IVA can have similar symptoms starting when they are older (up to around 5 years of age). Problems are often brought on by an infection (such as a tummy bug or a cold).
  • Other children with IVA may have less dramatic symptoms. These children may gain weight slower than expected  or they may have delayed milestones (such as sitting or talking).
  • IVA results from faults in a specific gene. One of these faults, called the 932C>T variant, causes a very mild form of IVA. There is a specific test to check whether an affected baby has this form of IVA. 

All children with IVA may experience intermittent deterioration following a minor illness (such as a cold or a tummy bug) and precautions are needed at these times.

Treatment

Treatment usually involves a low protein diet and medicines (carnitine and glycine). The diet reduces the formation of harmful chemicals and the drugs help the body to get rid of them.

If the child gets an infection, normal food should be stopped. Instead, the child is given special drinks containing plenty of sugar (the emergency regimen). If the drinks are vomited or refused, the child should be taken to hospital and given glucose  into a vein.

Effectiveness of Treatment

With early diagnosis and treatment, most children with IVA develop normally. Without treatment, IVA can cause permanent brain damage and learning difficulties. Treatment cannot reverse brain damage that has already happened.

 

 

Positive predictive value 30% (Mean EU data – see report)
Sensitivity Approx 100%
Screening index metabolite Isovaleryl carnitine, C5
Confirmatory test Plasma acylcarnitines, urinary organic acids