COL1A2 and osteogenesis imperfecta: The oim mutation is very similar to the first-identified mutation causing human osteogenesis imperfecta (autosomal-recessive Sillence type III), in which a four-nucleotide deletion (c.4001_4004del) causes a frameshift [p.(Asn1334Serfs*34)] to alter the last 33 amino acids of the α2 chain of type I procollagen (Pihlajaniemi et al., 1984).