2-Aminoadipic Aciduria 2 Oxoadipic Aciduria

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2-Aminoadipic 2-Oxoadipic Aciduria is a rare metabolic disorder characterised by high levels of compounds known as 2-oxoadipate and 2-hydroxyadipate in the urine, and elevated levels of the compound 2-aminoadipate in the blood. This is a genetic disorder that is linked to a defect in the normal breakdown of the essential amino acid lysine and hydroxylysine in the body.

We do not know the exact incidence. This disorder is very rare. Over 20 individuals are known to have this disorder.

Over half of people who have this condition do not show any symptoms (asymptomatic).

Those who do show symptoms have variable clinical presentation including:

• Low muscle tone (hypotonia)
• A delay in reaching developmental milestones
• Mild to severe intellectual disability
• Speech and language difficulties
• Poor coordination of muscle movements including gait abnormality, speech changes, and abnormal eye movements (ataxia)
• Epilepsy
• Behavioural disorders i.e. attention deficit hyperactivity disorder
• Small head size (microcephaly)

This disorder can be diagnosed using blood and urine tests. Exome sequencing can confirm diagnosis by identifying problems in the DHTKD1 gene.

There is no specific treatment or cure for this disorder. Any treatment given aims to provide relief for any symptoms that are present and to ensure the highest level of support and care available. The prognosis is variable, one child who have presented with symptoms is reported to have attended mainstream school with ongoing management of symptoms, a second still struggled with speech and language difficulties requiring further support. The antiepileptic drug, vigabatrin, should be avoided.

This disorder is believed to be autosomal recessive, which means it 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 this disorder is inherited. They can also tell you about genetic testing for the rest of your family.

References are available on request. Please contact us by phoning 0845 241 2173 or emailing contact@metabolicsupportuk.org [Resource Library No: AAP072].