AICAR Transformylase/IMP Cyclohydrolase Deficiency

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AICAR Transformylase/IMP Cyclohydrolase Deficiency is a very rare disorder which is caused by a defect in the ATIC gene.

This is a very rare disorder affecting less than 1 in a million people worldwide. There have been 4 clinical reports of this condition worldwide so far.

There is not a great deal of information about this disorder so symptoms and severity may vary greatly.

Before birth, routine tests may show growth delays and low levels of amniotic fluid (the fluid surrounding an unborn baby during pregnancy). Babies may be born with low muscle tone (hypotonia).

Delays in reaching growth and developmental milestones such as crawling or sitting unaided are evident during the first year. Some milestones will be achieved with age but the child is unlikely to be able to speak fluently or be able to walk. Epilepsy also often starts in first year of life with varying type and severity.

Other symptoms include:

• Severe to profound learning difficulties
• Vision problems including severe long-sightedness leading to sight loss
• Severe sideways curvature of the spine (scoliosis) which may appear during childhood
• Dimples on the knees, elbows, and shoulders
• Distinguishable facial features including an upturned nose, bushy eyebrows and long eyelashesLess common symptoms include:
• Heart defects apparent from birth
• Liver problems including an enlarged liver and a build up of fat cells in the liver
• Mild anomalies in the development of the genitals
• Calcium deposits in the kidney (nephrocalcinosis)

This disorder may be suspected through gene sequencing tests which examine the DNA found in cells. It may also be suspected following a specialised urine test showing high levels of AICA-riboside. Further specialised analysis programs can confirm diagnosis.

Treatment is based on managing the symptoms that are present and on providing care and support for the individual. Due to the variety of symptoms present, it is likely that a number of different medical specialities and wider agencies will be involved in the care and management of those diagnosed with this conditions. The prognosis is unknown due to the rarity of the condition. All reported individuals to date have required widespread support and management.

This disorder 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 this disorder. 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.

References are available on request. Please contact us by phoning 0845 241 2173 or emailing contact@metabolicsupportuk.org [Resource Library No: APPN06].