ATN1

Clinical Characteristics

ATN1-related neurodevelopmental condition is due to very small ‘spelling mistakes’ in the gene that stop it from working properly. Only 10 children, the oldest being 9 years old, are currently known around the world with this type of ATN1-related condition, and we are still learning more about this condition. 

Features of ATN1-related  neurodevelopmental condition can include:

  • Delayed motor (‘movement’) skills: To date, all individuals with ATN1-related disorder have been floppy (low tone or ‘hypotonia’) as babies, and slower to gain their ‘motor milestones’, such as the ability to roll, sit or stand.
  • Delayed cognitive (‘thinking’) skills: All individuals have had a diagnosis of ‘global developmental delay’ which means that they have been slower to gain all their milestones, and have required additional support with, for example, physiotherapy, occupational therapy and speech and language therapy.
  • Delayed speech and language (‘communication’) skills: All affected individuals had delays in their speech and language development. Some individuals are able to communicate using different sounds, and one child so far has the ability to use single words to communicate.
  • Seizures: Some individuals have developed epileptic seizures, that typically have been able to be well controlled with medication. 
  • Gastrointestinal: People with ATN1-related disorder may have difficulties gaining weight as infants and ongoing difficulties with feeding, eating and weight gain. Gastro-oesophageal reflux (acid reflux), difficulties coordinating sucking and swallowing and constipation are common but can respond to treatments. Some children have needed to be fed by gastrostomy ‘G’ tube or by TPN (total parenteral nutrition).
  • Brain and spine: Some individuals with ATN1-related condition have had normal imaging (CT or MRI scans) of their brain and spine, but in other individuals differences with how the brain has been formed or the appearance of the base of the skull and start of the spine have been noted on these checks.
  • Cardiovascular: Some individuals with ATN1-related condition have been born with a difference in how their hearts were formed or function, such as having ‘holes in the heart’ (VSD or ASD). These differences are detectable using a heart scan or echocardiogram.
  • Kidney and bladder: Some individuals with an ATN1-related condition have had bladder or urinary tract infections, needing treatment with antibiotics, and some have had differences in the appearance of their kidneys or bladder on ultrasound scans.
  • Hearing and vision (eye sight): Repeated middle ear infections, difficulties hearing including sensori-neural hearing impairment and difficulties with vision (cortical visual impairment) have been described.
  • Respiratory and sleep: Some individuals with an ATN1-related condition have had difficulties with chest infections or with their breathing and sleeping patterns and have needed treatment with antibiotics, and extra support of their breathing, for example with oxygen or special breathing support (‘CPAP’).
  • Craniofacial: A recognisable pattern of facial features may also be present. Some individuals have been described as having small differences in the appearance of their hairline, eyes, nose, mouth and ears, which may be recognised by a doctor specialising in the examination of children with genetic conditions.  

These features become present by early childhood. This is a genetic condition and is not related to environmental exposures or events during pregnancy or in early infant life.