Table 2

Summary of MNNG-induced (40 nm) HPRT hot spots in human TK6 cells

TK6 MNNG (40 nm) induced mutational hot spots.

bp PositionaExon/intronbSequence contextcMutation typedPoint mutant fractionePhenotypic ΔfSomatic mutationsgGerm-line mutationsh
208Exon 3AAG GGG GGCG > A1.E-01Gly- > Arg62
209Exon 3AAG GGG GGCG > A1.E-01Gly- > Glu53
IVS4-1Intron 4ctag AATG > A1.E-02Splice site00
400Exon 5GTG GAA gtaG > A2.E-02Glu- > Lys40
IVS5+ 1Intron 5GAA gtaaG > A1.E-02Splice site21
IVS5+ 5Intron 5taagttcG > A4.E-03Splice site10
IVS6+ 1Intron 6A AGgtatG > A1.E-01Splice site31
508Exon 7CCA CGA AGTC > T7.E-03Arg- > stop156
IVS7+ 5Intron 7taagtgaG > A1.E-02Splice site12
538Exon 8GTT GGA TTTG > A1.E-02Gly- > Arg21
569Exon 8GTA GGA TATG > A2.E-02Gly- > Glu10
580Exon 8CTT GAC TATG > A4.E-02Asp- > Asn31
599Exon 8TTC AGG GATG > A1.E-02Arg- > Lys30
IVS8+ 1Intron 8AAT gtaaG > A1.E-02Splice site40
  • a Column 1, mutational hot spot position (A of ATG is nucleotide 1 for mutations occurring in coding sequences; intron mutations are represented by the intron number and donor or acceptor site.

  • b Column 2, the affected exon/intron.

  • c Column 3, sequence context on the untranscribed DNA strand (uppercase letters indicate coding sequences; lowercase letters indicate intron sequences). Bold characters indicate the changed bp or sequence; underlining highlights local repeat sequences.

  • d Column 4, mutation type.

  • e Column 5, observed mutant fraction (mfi).

  • f Column 6, expected phenotypic change.

  • g Column 7, number of times the mutation was observed out of 458 6TGR mutants from peripheral T-lymphocytes of normal individuals.

  • h Column 8, number of times the mutation was observed out of 108 Lesch-Nyhan patients.