In Vitro Mammalian Chromosome Aberration Test (OECD 473)

Screening and Regulatory Support

  • The chromosome aberration test (CAT) is designed to evaluate the potential of a test compound to induce structural chromosomal abnormalities such as breaks and exchanges.
  • It can be performed in primary human peripheral blood lymphocytes (HPBL) or established cell lines, such as Chinese hamster ovary (CHO) cells.
  • Cultures are incubated with several concentrations of the test compound for 3 to 4 hours in the presence and absence of metabolic activation (S9) and for 21 hours in the absence of S9.
  • A positive outcome is characterized by a statistically significant, dose-dependent increase in aberrant cells that exceeds historical negative control limits.

Metaphase spread of human lymphocyte showing multiple chromosome aberration
Figure: Metaphase spread of human lymphocyte showing multiple chromosome aberrations

When to Perform

  • Screening
  • IND-enabling studies
    • As part of the ICH S2(R1) standard battery
  • REACH requirement
    • As part of Annex VIII testing

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