The associated spreadsheet contains corrections to the location of the molecular lesion for some of the X chromosome lethal alleles originally described in FBrf0223478. In each case the mutant allele has undergone a single base change in the codon listed in the 'Control sequence' columns (G and H), to give the mutant codon listed in the 'Mutation found' columns (I and J), at the location given in the R6 coordinate column (B).