The conditions associated with defects in the COL27A1 gene are inherited in an autosomal recessive manner and are caused by two abnormal copies of the COL27A1 gene, each inherited by each of the parents.
The main disorder associated with defects in the COL27A1 gene, Steel syndrome, is caused by the change of a Glycine amino acid to an Arginine amino acid at the position 697 of the COL27A1 produced protein, collagen XXVII. Other patients have been reported with mutations in the gene that result in the collagen XXVII protein not being produced by the cells. Collagen XXVII is produced by cartilage cells and it is important for the correct lay out of the matrix that forms the bones during development of the skeleton. Therefore, loss of this protein or abnormalities in the lay out due to an abnormal collagen XXVII protein can result in the skeletal features observed in patients.