Partial tetrasomy 12pter-12p12.3 in a girl with Pallister-Killian syndrome: extraordinary finding of an analphoid, inverted duplicated marker


Cytogenetic analysis in a girl with multiple congenital anomalies indicating Pallister-Killian syndrome (PKS) showed a supernumerary marker chromosome in 1/76 lymphocytes and 34/75 fibroblast metaphases. GTG-banding pattern was consistent with the chromosomal region 12pter-12q11. While fluorescence-in-situ hybridisation (FISH) with a whole chromosome 12 painting probe confirmed the origin of the marker, a chromosome 12 specific α-satellite probe did not hybridise to it. FISH analysis with a specific subtelomeric probe 12p showed hybridisation to both ends of the marker chromosome. High-resolution multicolour-banding (MCB) studies revealed the marker to be a der(12)(pter→p12.3::p12.3→pter). Summarising the FISH information, we defined the marker as an inverted duplication of 12pter-12p12.3 leading to partial tetrasomy of chromosome 12p. In skin fibroblasts, cultured at the patient's age of 1 year and 9 years, the marker chromosome was found in similar frequencies, even after several culture passages. Therefore, we consider the marker to have a functional centromere although it lacks detectable centromeric α-satellite sequences. To the best of our knowledge, this is the first proven analphoid marker of chromosome 12. Molecular genetic studies indicated that this marker is of paternal origin. The finding of partial tetrasomy 12pter-12p12.3 in our PKS patient allows to narrow down the critical region for PKS.


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We thank Prof Dr J Kömpf for LDH diagnosis.

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Correspondence to Andreas Dufke.

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Dufke, A., Walczak, C., Liehr, T. et al. Partial tetrasomy 12pter-12p12.3 in a girl with Pallister-Killian syndrome: extraordinary finding of an analphoid, inverted duplicated marker. Eur J Hum Genet 9, 572–576 (2001).

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  • Pallister-Killian syndrome (PKS)
  • partial tetrasomy 12p
  • analphoid marker chromosome
  • PKS critical region
  • multicolour banding (MCB)

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