Heterozygous COL1A2 mutations are associated with osteogenesis imperfecta types II-IV (MIM# 166210, 259420, 166220) and Ehlers-Danlos syndrome, type VIIB (MIM #130060). The vast majority of reported COL1A2 mutations, including intragenic copy number changes, result in a structurally abnormal protein product and pathogenesis by a dominant-negative, rather than a dosage sensitivity-type, mechanism (see PMID 17078022 and OMIM for reviews). Any identified copy number changes within this gene will need specific scrutiny to determine potential pathogenesis. Homozygous and compound heterozygous null COL1A2 mutations are associated with the autosomal recessive condition, Ehlers-Danlos syndrome, cardiac valvular form (MIM #225320). When reported, carrier parents had no evidence of valvular heart disease.