Human Genetics

, Volume 87, Issue 1, pp 1–5 | Cite as

Replication asynchrony between homologs 15q11.2: Cytogenetic evidence for genomic imprinting

  • Yoshinori Izumikawa
  • Kenji Naritomi
  • Kiyotake Hirayama
Original Investigations


Replication kinetics of the Prader-Willi syndrome critical region (15q11.2) was investigated in seven normal healthy adult females using RBG replication bands. Replication asynchrony between homologs 15q11.2 was identified consistently in about 40% of cells in all individuals. It was limited to the stages in which Xp22, Xp11, Xq13 and Xq24/26 were visible in the late-replicating X chromosome. This asynchrony suggested that replication timing overlapped between 15q11.2 and the early replicating R-bands of the late X chromosome in some cells, and that the difference in replication timing between homologs was probably related to genomic imprinting; the latter has been suggested as a pathogenetic basis of Prader-Willi syndrome. As a result of an analysis of the proportions of asynchronous and synchronous cells in each replication stage, two types of cells were deduced providing 1∶1 methylation mosaicism of genomic imprinting was assumed. The first type was composed of cells with normal replication in one homolog and delayed replication in the other. The second type was composed of cells with normal replication in both homologs. Our results provide cytogenetic evidence of methylation mosaicism for mammalian genomic imprinting.


Internal Medicine Metabolic Disease Adult Female Critical Region Healthy Adult Female 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


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Copyright information

© Springer-Verlag 1991

Authors and Affiliations

  • Yoshinori Izumikawa
    • 1
  • Kenji Naritomi
    • 1
  • Kiyotake Hirayama
    • 1
  1. 1.Department of PediatricsUniversity of the Ryukyus School of MedicineOkinawaJapan

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