Stickler syndrome. A mutation in the nonhelical 3' end of type II procollagen gene
N. N. Ahmad, J. Dimascio, R. G. Knowlton and W. S. Tasman
Wills Eye Hospital, Philadelphia, Pa, USA.
BACKGROUND: All of the mutations in the type II procollagen (COL2A1) gene
that have been identified in families affected with Stickler syndrome have
been located primarily in the triple helical region of the gene. We report
what we believe is the first premature stop codon in the globular
C-propeptide region encoded by the COL2A1 gene, in a family affected with
Stickler syndrome. DESIGN: Genomic DNA from affected and unaffected family
members of this three-generation family was amplified using the polymerase
chain reaction. The polymerase chain reaction products were directly
sequenced for DNA analysis. RESULTS: Direct sequencing showed a single base
deletion in exon 50, resulting in a premature stop codon in exon 51 in the
globular C-propeptide of COL2A1 gene in all affected members. CONCLUSIONS:
These results implicate premature stop codons as a common cause of Stickler
syndrome. The location of this premature stop codon in the far end of the
nonhelical 3' end of the gene indicates that a truncated C-propeptide of at
least 84 amino acid residues is inadequate for the functional gene product.
