Pyruvate Dehydrogenase Phosphatase Deficiency

What else is it called?

  • PDPD
  • PDHD

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What causes it?

Pyruvate Dehydrogenase Phosphatase Deficiency (PDPD) is a very rare form of Pyruvate Dehydrogenase Deficiency characterised by a build-up of lactic acid in the body (lactic acidaemia) in the first month after birth (neonatal period).

The disorder is caused by faults (mutations) in the PDP1 gene. This gene provides instructions for an enzyme (pyruvate dehydrogenase phosphatase isoform 1), which regulates the activity of the pyruvate dehydrogenase complex. The PDH complex plays an important role in the pathways that convert energy locked in food, into a form that the cells in your body can use.

How common is it?

PDPD is extremely rare, with only 3 cases (two brothers and one unrelated female) being reported.

What are the signs and symptoms?

Onset for this disorder occurs in the first few days of life.

Symptoms in the small number of reported cases include:

  • Decreased muscle tone (generalised hypotonia)
  • Increased lactate in blood (lactic acidosis) and organs
  • Low blood sugar (hypoglycaemia)
  • Developmental delay

However, symptoms can vary from person to person and it is likely that this list does not reflect all of the possible problems.

How is it diagnosed?

A doctor will usually give you / your child a clinical examination. Your family history will be checked, to see if anyone in your family has had the disease, or a similar metabolic disease.

The results of biochemical tests in blood and urine may indicate that the Pyruvate Dehydrogenase Complex is not functioning properly, but to confirm the diagnosis of PDPD it will be necessary to undertake genetic testing from a DNA sample.

Can it be treated?

There is no specific treatment or cure for PDPD. One treatment focuses on providing a different source of energy, with fats being preferred to carbohydrates (“carbs”). This high fat diet is known as the Ketogenic Diet. Other treatments such as sodium bicarbonate aim to correct the lactic acidosis caused by this condition.

Any treatment given aims to provide relief for the symptoms that are present and to ensure the highest level of support and care for your child and for your family. There is ongoing research underway to try and find a treatment for this disorder.

Do my family need to be tested?

PDPD can only be passed on to a child if both parents have a copy of the faulty gene. This is called autosomal recessive inheritance. If the child only inherits one copy of the faulty gene, they’ll be a carrier of the condition but won’t have the condition.

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.

Relevant Organisations


References are available on request. Please contact Helen Morris by phoning 0845 241 2173 or emailing [Resource Library No: AAP002].

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