Smith-Magenis syndrome deletion: A case with equivocal cytogenetic findings resolved by fluorescence in situ hybridization

R. C. Juyal, F. Greenberg, G. A. Mengden, J. R. Lupski, B. J. Trask, G. Van den Engh, E. A. Lindsay, H. Christy, K. S. Chen, A. Baldini, L. G. Shaffer, P. I. Patel

Research output: Contribution to journalArticlepeer-review


The availability of markers for the 17p11.2 region has enabled the diagnosis of Smith-Magenis syndrome (SMS) by fluorescence in situ hybridization (FISH). SMS is typically associated with a discernible deletion of band 17p11.2 upon cytogenetic analysis at a resolution of 400-550 bands. We present a case that illustrates the importance of using FISH to confirm a cytogenetic diagnosis of del(17)(p11.2). Four independent cytogenetic analyses were performed with different conclusions. Results of low resolution analyses of amniocytes and peripheral blood lymphocytes were apparently normal, while high resolution analyses of peripheral blood samples in two laboratories indicated mosaicism for del(17)(p11.2). FISH clearly demonstrated a 17p deletion on one chromosome of all peripheral blood cells analyzed and ruled out mosaicism unambiguously. The deletion was undetectable by flow cytometric quantitation of chromosomal DNA content, suggesting that it is less than 2 Mb. We conclude that FISH should be used to detect the SMS deletion when routine chromosome analysis fails to detect it and to verify mosaicism.

Original languageEnglish
Pages (from-to)286-291
Number of pages6
JournalAmerican Journal of Medical Genetics
Issue number3
Publication statusPublished - 1995


  • chromosome 17p11.2
  • del(17)(p11.2)
  • diagnosis
  • flow cytometry
  • flow karyotyping
  • mosaicism

ASJC Scopus subject areas

  • Genetics(clinical)


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