Several errors have been detected in the electronic letter by Toyama et al (J Med Genet 2004;41:e74).

First, the abbreviations for Table 1 should read:

Ex, exon; (FAM)-,FAM-labelled; (HEX)-,HEX-labelled; (ROX)-,ROX-labelled; (NED)-,NED-labelled; UP, upstream; Pro, prometer; Int, intron; Fl, flanking; STR, short tandem repeat.

Second, the parenthesised section of the last sentence of the Results should read:

(7.3 ± 1.3 mmol/l (K287I) and 7.63 ± 1.0 mmol/l (M310I) compared to that of the wild type (3.8 ± 0.4 mmol/l).

In addition, in Ex4 of Table 3 the “Type” should read C235 (R79W), in Figure 1 “Euro. Am” is the abbreviation for “European American,” and in Table 4 the title should read “Catalytic activity of recombinant AMPD1 expressed in E. coli”.

We apologise for these errors.