Brain channelopathy

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Inclusion criteria:

  • Episodic disorder that often causes a combination of ataxia with walking problems, abnormal extra movements, stiff legs, weakness, headache and nausea.
  • Episodes lasting a few minutes or hours.
  • There may be a dystonic component and some patients are exhausted for many hours afterwards.
  • Attacks are not always the same, even with the same genetic defect.
  • Arms can be affected like legs
  • Migraine type headaches are frequently associated as is dysarthria
  • Some patients have a primary headache in the form of hemiplegic migraine (FHM), cluster headache, SUNCT or SUNA
  • MRI brain and cord to exclude common causes such as tumours, discs, demyelinating causes
  • Family history of often present in AD or AR forms, X linked pattern rare
  • Often drugs such as Lamotrigine or acetazolamide are effective

Individuals with severe or syndromic disease should be recruited according to standard guidance, typically as trios. Disease status of apparently unaffected participants should be determined according to standard clinical practice to detect cryptic disease.

In other cases, unaffected individuals should not be recruited. Recruitment in such families should favour multiplex families over single isolated cases. These singleton recruits will not contribute to the overall singleton monitoring metrics applied to GMCs.

Exclusion criteria

Prior genetic testing guidance

  • Results should have been reviewed for all genetic tests undertaken, including disease-relevant genes in exome sequencing data. The patient is not eligible if they have a molecular diagnosis for their condition.
  • Genetic testing should continue according to routine local practice for this phenotype regardless of recruitment to the project; results of these tests must be submitted via the ‘Genetic investigations’ section of the data capture tool to allow comparison of WGS with current standard testing.

PLEASE NOTE: The sensitivity of WGS compared to current diagnostic genetic testing has not yet been established. It is therefore important that tests which are clinically indicated under local standard practice continue to be carried out.

Prior genetic testing genes 

Testing of the following genes should be carried out PRIOR TO RECRUITMENT where this is in line with current local practice:

  • KCNA1, PRRT2 as appropriate
  • CACNA1A (only in dominant, long duration episodic ataxia)

Closing statement 

These requirements will be kept under continual review during the main programme and may be subject to change.

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