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18q syndrome

18q syndrome is a rare chromosomal anomaly where there is deletion of part of the long arm of chromosome 18.  Associated symptoms and findings vary widely, as does their severity.  Characteristic features include short stature, mental retardation and hypotonia, facial and distal skeletal abnormalities.  Chromosome 18q syndrome appears to result from spontaneous sporadic chromosomal error during very early embryonic development.

Clinical presentation

The presence of a syndrome are usually evident at or soon after birth. Although there is significant phenotypic variation, some features are relatively constant and include 1:

  • decreased growth
  • craniofacial dysmorphism
  • genital hypoplasia
  • limb abnormalities
  • neurological abnormalities
    • developmental delay and mental retardation
    • ocular movement disorders
    • seizures
    • autism

Radiographic features

MRI Brain

The appearance of the brain on MRI is dominated by abnormal white matter, particularly posteriorly and in the periventricular region. It is characterised by bilateral symmetric deep white matter hyperintensity on T2 weighted images, with associated involvement of the subcortical white matter also frequently encountered 1-2. The brainstem and and cerebellum are usually spared.

MR spectroscopy (MRS)

May demonstrate elevated choline in the white matter as well as elevated alpha-glutamate concentrations (resonates at 3.75ppm) 3

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