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Chromosome 18q paracentric inversion in a family with mental retardation and hearing loss

K M Keppler-Noreuil1, A J Carroll, S C Finley

  • 1Department of Pediatrics, University of Alabama at Birmingham, USA.

American Journal of Medical Genetics
|April 29, 1998
PubMed

Insights

A mother and child with chromosome 18 inversion experienced developmental delays and hearing loss. Molecular studies revealed a deletion in the MBP region, potentially explaining abnormal myelination and other symptoms in this 18q- syndrome case.

Area of Science:

  • Genetics
  • Molecular Biology
  • Neuroscience

Background:

  • A family presented with a paracentric inversion of chromosome 18 (46,XX,inv(18)(q21.1q23)).
  • The child exhibited features overlapping with 18q- syndrome, including microcephaly, developmental delay, and hearing loss.
  • Maternal relatives also reported mild mental retardation and hearing loss.

Observation:

  • The child displayed microcephaly, epicanthal folds, midface hypoplasia, abnormal ears, clubfeet, and hearing loss.
  • Brain MRI revealed abnormal myelination in the affected child.
  • The mother and other relatives had mild intellectual disability and hearing impairment.

Findings:

  • Molecular studies confirmed a deletion extending beyond the MBP locus (18q23) in both mother and child.
  • The deletion in the myelin basic protein (MBP) region is a potential cause of the observed abnormal myelination.
  • Clinical manifestations suggest disruption of genes within the deleted region or at the 18q21.1 breakpoint.

Implications:

  • This case highlights the potential role of the MBP locus and surrounding genes in 18q- syndrome phenotypes.
  • Further investigation of this family can help delineate genes critical for myelination and neurodevelopment.
  • Understanding these genetic disruptions may lead to better diagnosis and management of contiguous gene syndromes.

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