Additionally, individuals with autosomal recessive loss‐of‐function mutations of the Wnt‐β‐catenin inhibitor sclerostin (SOST) manifest sclerosteosis, type 1, which is characterized by progressive bone overgrowth throughout life 49, 50; whilst patients harbouring a homozygous 52 kb deletion containing an enhancer element downstream of the SOST gene develop van Buchem disease, which has a similar but milder skeletal phenotype compared to sclerosteosis, type 1 51, 52. The gene discussed is SOST; the disease is sclerosteosis.