Long chain acyl CoA dehydrogenase deficiency
What else is it called?
- Long-chain 3-hydroxyacyl-coenzyme A dehydrogenase deficiency
- Long-chain 3-hydroxy acyl CoA dehydrogenase deficiency
- Long-chain 3-OH acyl-CoA dehydrogenase deficiency
- Trifunctional protein deficiency type 1
- 3-hydroxyacyl-CoA dehydrogenase long chain deficiency
- LCHAD deficiency
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What causes it?
LCHAD deficiency is caused by an error in one of the genes you inherit from your parents. The HADHA and HADHB gene is responsible for making a protein that can break down fats called enzymes. The specific ones that this HADHA and HADHB genes make are called the mitochondrial trifunctional protein, which consists of three proteins (mitochondrial trifunctional proteins). LCHAD is one of these three proteins and needed for the breakdown of certain fats (long chain fatty acids). LCHAD deficiency prevents your child’s body from making or only partially making the substance that can break down certain fats (long chain fatty acids) for energy. As a result of your child being diagnosed with this disorder, their body can accumulate harmful intermediates which may be very damaging to their liver, heart muscles and eyes, particularly the retina.
LCHAD can be very serious and if your child is diagnosed with this condition, they may be at risk of serious health complications such as, breathing difficulties, heart problems, muscle break down and, in some, cases, sudden death.
How common is it?
Current research suggests that the prevalence of LCHAD deficiency is unknown. It is estimated that in the Finnish population of 1 – 62,000 pregnant woman have a chance of having a child with this deficiency. Prevalence of this metabolic condition is said to be lower within regions of the United States of America.
What are the signs and symptoms?
Signs and symptoms to look out for with this metabolic condition are:
- Low blood sugars (hypoglycaemia)
- Low ketone levels
- Lack of energy
- Difficulty feeding
- Low muscle tone
- Sensitive to light (photophobia)
- Outwards facing eye balls
- Enlarged heart muscle
- Loss of vision
- Neurological problems
- Muscle breakdown (Rhabdomyolysis)
Symptoms of this disorder can present from birth to upwards of 3 years of age. In late childhood, your child may experience other symptoms such as, muscle loss and loss of feeling in the arms and legs. Drinking plenty of water when your child has diarrhoea is important to maintain hydration and in keeping the correct electrolyte balance in the body. Electrolytes can be added to fluids in severe cases of diarrhoea.
Some of the symptoms of this condition can worsen during stressful situations such as, prolonged periods of fasting or during viral infections, when the body requires more energy, this would deplete the body’s glucose stores and the body would rely on breaking down fat for energy which it would be unable to do. Loss of feeling in hands and feet and loss of sight are chronical progressive symptoms.
How is it diagnosed?
If you or your child’s new born screening tests show abnormal levels of certain acylcarnitine species, LCHAD then this may be an indication of this LCHAD deficiency. Confirmation is needed by follow up tests to this may include urine and blood sample testing. Blood and urine tests would be performed to check for possible harmful levels of the build-up of the biproduct of this deficiency.
Another test which may be performed to diagnose LCHAD is Tandem mass spectrometry of organic acids in urine, and carnitines in blood spots. This allows the diagnosis to be unequivocally determined. A skin biopsy can be taken to test the enzyme levels required for the breakdown of long chain fatty acids. This test involves taking a sample from your skin with a small needle and testing the levels of this substance against threshold levels to diagnose this disorder. Your genes can be tested for the metabolic disorder, this may help to diagnose the condition early to set up treatment.
Diagnosing LCHAD deficiency is complicated, this is due to the similarity of signs and symptoms to other disorders such as Reye syndrome. Most cases of Reye syndrome are associated with using aspirin during viral infections.
Can it be treated?
LCHAD deficiency currently has no cure, this condition is currently managed with dietary intervention with the assistance of a dietitian. Treatment for this metabolic disorder encourages your child to avoid prolonged periods of fasting and avoiding the intake of long chain fatty acids. Your dietitian may prescribe your child with an intravenous glucose solution to be administered overnight or if the child is unwell, this would be done to avoid prolonged periods of fasting overnight and to make sure that the glucose stores do not become fully depleted. Some children take corn starch before bed to avoid glucose stores becoming depleted. Medium chain fatty acids supplementation (MCT oils) can be taken so that the body can break down these fats if glucose stores do become depleted. this Information on the management of this condition will be fully explained to you and demonstrated to you by your dietitian.
AN ACT sheet is available for this condition, this is a sheet that a health care professional must follow with information about LCHAD deficiency and protocols to follow.
Do my family need to be tested?
LCHAD deficiency can only be passed on to a child if both parents have a copy of the faulty gene. This is called autosomal recessive inheritance. A person who has a copy of the faulty gene is known as a carrier.
If both parents are carriers, their child has a one in four (25%) chance of inheriting the disorder, and a one in two chance (50%) of being a carrier. This is the same for each child the parents have.
If the child only inherits one copy of the faulty gene, they will be a carrier but will not have the disorder. In some rare cases, carriers have had mild symptoms of the disorder for which they carry the faulty gene.
Once you are diagnosed, you can speak to a genetic counsellor. They can explain how you may have inherited LCHAD deficiency. They can also tell you about genetic testing for the rest of your family. They can provide advice and support if you go on to have children of your own.
If you have previously had a child with LCHAD deficiency and go on to have further children, their New-born Screening test should be carried out within 24-48 hours of birth.