On the other hand, the mean C-reactive protein (CRP) level during 2 years prior to the diagnosis of AA-amyloidosis was significantly higher in the patients with larger numbers of the gamma allele at the SAA1 locus (Spearman's correlation coefficient: 0.34, P<0.05).
Chronically elevated A-SAA concentrations are a prerequisite for the pathogenesis of secondary amyloidosis, a progressive and fatal disease characterized by the deposition in major organs of insoluble plaques composed principally of proteolytically cleaved A-SAA, and may also contribute to physiological processes that lead to atherosclerosis.
These results suggest that there is probably differential amyloidogenicity amongst the different SAA1 isoforms and indicate that homozygosity for SAA1 alpha and SAA1 gamma in the different populations is a significant risk factor for development of AA amyloidosis.
Furthermore, we report that there was a significant difference in the observed numbers of SAA1 alleles between rheumatoid arthritis patients with AA-amyloidosis and the control population (chi 2(2) = 11.59, p = 0.003) with a higher frequency of gamma-allele in the AA-amyloid group (0.70 vs. 0.37).
Serum amyloid A protein (SAA) is a precursor for a major component of amyloid fibrils, which, upon deposition, cause secondary amyloidosis in diseases such as rheumatoid arthritis.