- Neuronal migration abnormality: Bilateral neuronal migration abnormality, confirmed on MRI or pathology, normal TORCH screen
- Posterior fossa abnormality: Cerebellar vermis agenesis /hypoplasia < 5th percentile and / or bilateral cerebellar hemisphere hypoplasia /atrophy, confirmed on MRI or pathology
- Midline brain abnormalities: Absent cavum septum pellucidum or holoprosencephaly or complete / partial agenesis of the corpus callosum, confirmed on MRI or pathology
- Severe ventriculomegaly with posterior ventricle measuring > 15mm: non-obstructive, normal spine anatomy, confirmed on MRI or pathology, normal TORCH screen
- Microcephaly: Head circumference measuring <3rd percentile, confirmed on fetal MRI or pathology, normal TORCH & VZV screen.
- For all: Both parents MUST be available to provide a blood sample for testing.
- Midline brain abnormalities: maternal exposure to illicit drugs and alcohol
- Severe ventriculomegaly: intracranial haemorrhage of any underlying cause; twin pregnancy related problems.
- Microcephaly: Parental head circumference measuring <3rd percentile, normal HC/AC and HC/FL ratios.
- For all: A known genetic or chromosomal cause.
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:
- Chromosome microarray
- ASPM and other genes dictated by the phenotype
These requirements will be kept under continual review during the main programme and may be subject to change.
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