EXPRESSION AND SEQUENCE OF THE GENE FOR TISSUE INHIBITOR OF METALLOPROTEINASES IN PATIENTS WITH ABDOMINAL AORTIC-ANEURYSMS

Purpose: The tissue inhibitors of metalloproteinases (TIMPs) are major inhibitors of several enzymes that are destructive to connective tissue, and TIMP-1 has been reported to be deficient in the wall of abdominal aortic aneurysms. This deficiency could represent failure of expression resulting from either local tissue conditions or mutation in the primary structure of the gene (or one of its regulatory elements). Methods: Southern blotting techniques were used to examine the possibility of global deletions or inserts in the gene (14 patients); Northern blot techniques were performed to examine the expression of the mRNAs in cultured fibroblasts under basal conditions (six patients); and sequence analysis of the cDNA derived from fibroblast mRNAs was done after amplification by polymerase chain reaction (six patients). Results. The Southern blots revealed a normal distribution of the known alleles of the gene without unique restriction-length polymorphisms. Fibroblast expression of TIMP mRNA was normal under basal conditions. Sequence analysis of the cDNAs revealed an identical-point polymorphism in two of the six patients (a single base pair substitution of C --> T at the third position in codon 101), but the amino acid was conserved. Conclusion: The studies reported here do not support the hypothesis that deficiency of TIMP-I in specimens of aorta of patients with abdominal aortic aneurysms results from a primary genetic defect.