Hypotonia-Cystinuria Syndrome

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Hypotonia-Cystinuria syndrome [HCS] is a very rare autosomal recessive metabolic condition. To date, there is very little information upon this metabolic disorder due to the limited number of individuals who have been diagnosed with this order, more research is required in this area.

HCS is a very rare metabolic condition which has roughly affected 14 individuals to date worldwide, with no preference over males or females or ethnicities.

HCS onset as early as neonatal and can be diagnosed in infancy. Symptoms may vary from individual to individual.

• Intellectual disability
• Neonatal seizures
• Growth delay
• Distinct body dysmorphia
• Growth impairment
• Infantile hypotonia
• Global developmental delay
• Minor facial dysmorphism
• Ptosis [drooping of the lower eye lid]

Currently, there is very little information upon diagnosis of this condition, more research is required to assert how this metabolic condition is diagnosed.

Treatment recommendation for this very limited due to the limited research into this metabolic condition. Management of this condition may depend upon the specific symptoms experienced per individual.

It has been suggested that infantile hypotonia may respond to treatment with pyridostigmine.

Hypotonia-cystinuria syndrome 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 hypotonia- cystinuria syndrome. 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 MCADD and go on to have further children, their Newborn Screening test should be carried out within 24-48 hours of birth.

References are available on request. Please contact us on 0800 652 3181 or by emailing contact@metabolicsupport.org.

Please note calls to 0800 numbers are free from UK landlines and mobiles. Calls from business lines may be charged – please check with your provider.

This information about metabolic diseases is provided by Metabolic Support UK and is intended for educational purposes only. It should not be used for diagnostic or treatment purposes.

Should you require more detailed information please contact Metabolic Support UK by email (contact@metabolicsupport.org) or by telephone ( 0800 652 3181). For specific medical information regarding a disorder or individual please contact your GP or Paediatrician. Metabolic Support UK accepts no responsibility for any errors or omissions nor does Metabolic Support UK assume any liability of any kind for the content of any information contained within this summary or any use that you may make of it.