The rates of G:C-->T:A and G:C-->C:G transversions at CpG dinucleotides in the human factor IX gene

Am J Hum Genet. 1994 May;54(5):831-5.


We have identified eight independent transversions at CpG in 290 consecutive families with hemophilia B. These eight transversions account for 16.3% of all independent transversions in our sample, yet the expected frequency of CpG transversions at random in the factor IX gene is only 2.6% (P < .01). The aggregate data suggest that the two types of CpG transversions (G:C-->T:A and G:C-->C:G) possess similar mutation rates (24.8 x 10(-10) and 20.6 x 10(-10), respectively), which are about fivefold greater than the comparable rates for transversions at non-CpG dinucleotides. The enhancement of transversions at CpG suggests that the model by which mutations occur at CpG may need to be reevaluated. The relationship, if any, between deamination of 5-methyl cytosine and enhancement of transversions at CpG remains to be defined.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Base Sequence
  • Codon / genetics
  • Dinucleoside Phosphates / analysis
  • Factor IX / genetics*
  • Hemophilia B / blood
  • Hemophilia B / genetics*
  • Humans
  • Models, Genetic
  • Molecular Sequence Data
  • Point Mutation*
  • Polymorphism, Genetic
  • Promoter Regions, Genetic


  • Codon
  • Dinucleoside Phosphates
  • cytidylyl-3'-5'-guanosine
  • Factor IX