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American Journal of Human Genetics logoLink to American Journal of Human Genetics
. 1990 Sep;47(3):493–498.

The isochromosome 18p syndrome: confirmation of cytogenetic diagnosis in nine cases by in situ hybridization.

D F Callen 1, C J Freemantle 1, M L Ringenbergs 1, E Baker 1, H J Eyre 1, D Romain 1, E A Haan 1
PMCID: PMC1683854  PMID: 2393023

Abstract

Nine cases are described of tetrasomy 18p resulting from the presence of an isochromosome 18p [i(18p)]. The initial diagnosis of i(18p) was by standard cytogenetic techniques and was confirmed by in situ hybridization with a biotinylated alphoid probe (L1.84) specific for the pericentric region of chromosome 18 and with a tritium-labeled chromosome 18 probe (B74) which hybridizes to the D18S3 locus situated at 18p11.3. The clinical features of the cases are summarized and shown to constitute a distinct and recognizable syndrome. Common features were low birth weight, a characteristic facies, neonatal hypotonia with subsequent limb spasticity, short stature, microcephaly, mental retardation, and seizure disorders. On the basis of size and cytogenetic banding a marker chromosome can be suspected to be an i(18p). In situ hybridization with the alphoid probe L1.84 provides confirmation of chromosome 18 origin. This more precise diagnosis will be an advantage in situations of pre- and postnatal diagnosis, since parents can be provided with a more confident prognosis for their child.

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.

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