WFS1 and Werner syndrome: 2011). The cause of WS is the loss‐of‐function mutations in wolframin (Wfs1) gene (Strom et al. 1998). Wfs1 is linked to the short arm of chromosome 4 p16.1 (Polymeropoulos et al. 1994; Collier et al. 1996). The Wfs1 gene encodes wolfamin (WFS1), a protein with 890 amino acid residues and a molecular mass of 100 kDa. WFS1 is a hydrophobic glycoprotein which contains nine transmembrane segments, with the N‐terminus localized in the cytoplasma and the C‐terminus in the endoplasmic reticulum lumen (Hofmann et al. 2003).