The pathogenic RECQ1 missense mutations (A195S, R215Q, R455C, M458K, and T562I) identified in breast cancer patients include highly conserved amino acid residues in catalytic domains of RECQ1 (Figure 1B), and the recombinant proteins show complete (R215Q, R455C, M458K, and T562I) or partial (A195S) loss of helicase activity in vitro. This evidence concerns the gene RECQL and breast carcinoma.