Table 1

Summary of spontaneous HPRT hot spots in human TK6 cells after 60 in vitro doublings

bp PositionaExon/intronbSequence contextcMutation typedPoint mutant fractionePhenotypic ΔfSomatic mutationsgGerm-line mutationsh
258-9 or 257-8Exon 3G AA(T A)GA AAT AGdel 25.E-03Frameshift00
265Exon 3GA AAT (A)GT GAdel 14.E-03Frameshift00
401 or 403Exon 5GTG G(AA gt)(aagt)tcdel 42.E-02Splice site loss00
435–437Exon 6AC(T) (T)(T)G CTTins T5.E-03Frameshift00
475Exon 6GTC AAG GTCA > T7.E-03Lys- > stop00
IVS6+ (2–5)Intron 6AG g(tatg)(tatg) acadel 44.E-03Splice site loss00
508Exon 7CCA CGA AGTC > T3.E-02Arg- > stop156
TT GTT (G (GA TTT GAA ATT CCA) G)AC AAG TTT GTTdel 157.E-03Frameshift00
538 or 539Exon 8
538Exon 8GTT GGA TTTG > A4.E-03Gly- > Arg21
556 or 557Exon 8GAC (A)(A)G TTTdel 14.E-03Frameshift00
569Exon 8GTA GGA TATG > A8.E-03Gly- > Glu10
580Exon 8CTT GAC TATG > A9.E-03Asp- > Asn31
581Exon 8CTT GAC TATA > T1.E-02Asp- > Val10
594Exon 8GAA TAC TTCC > A7.E-03Tyr- > stop00
  • a Column 1, mutational hot spot position (A of ATG is nucleotide 1 for mutations occurring in coding sequences.

  • 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 (mf1).

  • 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.