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A characteristic syndrome associated with microduplication of 8q12, inclusive of CHD7

Anna M Lehman1, Jan M Friedman, David Chai

  • 1Department of Medical Genetics, University of British Columbia, Canada.

European Journal of Medical Genetics
|September 24, 2009
PubMed

Insights

A rare genetic duplication involving the CHD7 gene on chromosome 8q12 was identified in a child with developmental delays and congenital anomalies. This finding suggests abnormal gene dosage may cause a CHARGE syndrome-like phenotype.

Area of Science:

  • Genetics
  • Developmental Biology
  • Pediatrics

Background:

  • CHARGE syndrome, typically caused by CHD7 mutations, presents with multiple congenital anomalies.
  • Genetic duplications in the 8q12 region, including CHD7, are rare causes of developmental disorders.

Observation:

  • A 4-year-old girl exhibited hypotonia, developmental delay, failure to thrive, cognitive impairment, and multiple congenital anomalies.
  • Array comparative genomic hybridization revealed a de novo tandem duplication of 6.9 Mb on chromosome 8q12, encompassing the CHD7 gene.

Findings:

  • The patient presented with a phenotype including Duane anomaly, Mondini malformation, deafness, ear malformations, and septal defects.
  • This case, along with a previously reported individual, suggests a recurrent pattern of anomalies in 8q12 duplications involving CHD7.

Implications:

  • Overlapping duplications of the 8q12 region containing CHD7 may lead to a distinct phenotype due to abnormal gene dosage.
  • Further research into CHD7 dosage effects is warranted for understanding developmental disorders and genetic syndromes.

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