A) Amino acid sequence of the region immediately upstream of the PALB2 WD40-repeat. The in-frame deletion, created by the skipping of exon 6, is indicated by the black box. The position of beta-strand 7D and the upstream region of helical propensity are indicated by the magenta arrow and yellow box respectively. The amino acids visible in the X-ray crystal structure of the wild-type PALB2 WD40-repeat (PDB: 2W18) are also indicated. B) In the wild-type protein Leu861 of beta-strand 7D sits in a small hydrophobic pocket lined by the indicated amino acids. C) Molecular cartoons showing the N-terminal part of the WD40-repeat (cyan). (Left) the labelled amino acids (coloured asterisks), on one face of the upstream helical element (yellow), resemble structurally and spatially, those of the 7D beta-strand (Right, magenta).