Homozygous mutation of E35, which is located at the N-terminal end of α1 helix and which makes contacts to the variant residues 16 and 19 in PTH/PTHrP, is found in the rare Eiken syndrome characterized by delayed bone mineralization and epiphyseal dysplasia (Moirangthem et al, 2018). This evidence concerns the gene PTHLH and Eiken syndrome.