18q syndrome is a rare chromosomal anomaly where there is a 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 a spontaneous, sporadic chromosomal error during very early embryonic development.
The presence of a syndrome is 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
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 cerebellum are usually spared.
MR spectroscopy (MRS)
MRS demonstrates elevated white matter choline and alpha-glutamate concentrations (resonates at 3.75ppm) 3.
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- 5.Kumada T, Ito M, Miyajima T et-al. Intractable epilepsy (apneic seizure) in an infant with 18q deletion syndrome. No To Hattatsu. 2004;35 (6): 521-6. Pubmed citation