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.
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
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.
- 1. Loevner LA, Shapiro RM, Grossman RI et-al. White matter changes associated with deletions of the long arm of chromosome 18 (18q- syndrome): a dysmyelinating disorder? AJNR Am J Neuroradiol. 17 (10): 1843-8. AJNR Am J Neuroradiol (abstract) - Pubmed citation
- 2. Lancaster JL, Cody JD, Andrews T et-al. Myelination in children with partial deletions of chromosome 18q. AJNR Am J Neuroradiol. 2005;26 (3): 447-54. AJNR Am J Neuroradiol (full text) - Pubmed citation
- 3. Häusler M, Anhuf D, Schüler H et-al. White-matter disease in 18q deletion (18q-) syndrome: magnetic resonance spectroscopy indicates demyelination or increased myelin turnover rather than dysmyelination. Neuroradiology. 2005;47 (1): 83-6. doi:10.1007/s00234-004-1309-9 - Pubmed citation
- 4.Linnankivi TT, Autti TH, Pihko SH et-al. 18q-syndrome: brain MRI shows poor differentiation of gray and white matter on T2-weighted images. J Magn Reson Imaging. 2003;18 (4): 414-9. doi:10.1002/jmri.10383 - Pubmed citation
- 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