WES identified mutations in WNT1 as the cause of autosomal dominant early-onset osteoporosis in some families; however, as mutations in WNT1 were also identified in consanguineous families with autosomal recessive osteogenesis imperfecta it would perhaps be more correct to regard the families diagnosed with AD osteoporosis as having a subtle form of OI and/or a monogenic skeletal dysplasia rather than the common polygenic disease of osteoporosis [30,31]. The gene discussed is WNT1; the disease is skeletal dysplasia.