COL1A1 and osteogenesis imperfecta: ,29 Whereas some case series report no evidence for a correlation between the disease-causing genes COL1A1 and COL1A2 and CVD, others report a higher frequency of cardiovascular abnormalities in individuals with OI caused by variants in COL1A1 compared to COL1A2.30,31 However, this literature is very limited and based on small case series without statistically significant genotype – phenotype correlations.