Identification of an unusual marker chromosome by spectral karyotyping

Bing Huang, Yi Ning, Alien N. Lamb, Constance J. Sandlin, Mehdi Jamehdor, Thomas Ried, James Hartley

Research output: Contribution to journalArticlepeer-review


We ascertained a newborn girl with multiple congenital anomalies including severe hypotonia, cardiovascular defects, hearing loss, central nervous system anomalies, and facial anomalies. The infant died at 12 days. Cytogenetic analysis showed a de novo supernumerary marker chromosome. Fluorescence in situ hybridization (FISH) with a combination of chromosome specific alphasatellite probes and an all-human centromere probe failed to show hybridization to the marker, indicating that the marker chromosome lacked detectable alpha satellite sequences. Spectral karyotyping (SKY) was performed and showed that the marker was chromosome 15 in origin. This was confirmed by FISH with a 15q specific subtelomeric probe, which showed hybridization to both ends of the marker chromosome. Based on FISH information and G-banding pattern, the marker was determined to be an inverted duplication of 15q25-qter, leading to partial tetrasomy for chromosome 15. Although the marker chromosome lacked detectable centromeric alpha-satellite sequences, it seemed to have a functional centromere as it is mitotically stable. This observation is consistent with previous studies on acentric marker chromosomes, which suggested that the DNA sequence at the breakpoint could function similarly to alpha-satellite sequences once activated through marker formation.

Original languageEnglish (US)
Pages (from-to)368-372
Number of pages5
JournalAmerican journal of medical genetics
Issue number4
StatePublished - 1998


  • Alphasatellite sequence
  • Centromere
  • Fluorescence in situ hybridization
  • Marker chromosome
  • Spectral karyotyping
  • Tetrasomy of chromosome 15

ASJC Scopus subject areas

  • Genetics
  • Genetics(clinical)


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