Identification of a new heterozygous point mutation in the COL1A2 gene leading to skipping of exon 9 in a patient with joint laxity, hyperextensibility of skin and blue sclerae

A heterozygous deletion of exon 9 in the COL1A2-mRNA of a patient with symptoms of both the Ehlers-Danlos-Syndrome and the Osteogensis Imperfecta is described. In the genomic DNA of the patient, exon 9 is homozygously present. We identified a novel heterozygous point mutation in the splice donor site of intron 9, leading to a G-->A substitution in position +5. This mutation leads to heterozygous skipping of exon 9 in the COL1A2-mRNA of this patient. The deletion results in a shortened (by 18 amino acids) but in frame 12(1) chain, which probably leads to the formation of abberantly processed triple helices.