Predicting genetic risk factors for AA amyloidosis in Algerian patients with familial Mediterranean fever.

Renal amyloid-associated (AA) amyloidosis is a harmful complication of familial Mediterranean fever (FMF). Its occurrence involves polymorphisms and mutations in the Serum Amyloid A1 (SAA1) and Mediterranean Fever (MEFV) genes, respectively. In Algeria, the association between SAA1 variants and FMF-related amyloidosis was not investigated, hence the aim of this case-control study. It included 60 healthy controls and 60 unrelated FMF patients (39 with amyloidosis, and 21 without amyloidosis). All were genotyped for the SAA1 alleles (SAA1.1, SAA1.5, and SAA1.3), and a subset of them for the - 13 C/T polymorphism by using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Comparisons between genotype and allele frequencies were performed using Chi-square and Fisher tests. The SAA1.1/1.1 genotype was predominant in amyloid FMF patients, compared to non-amyloid FMF patients (p = 0.001) and controls (p < 0.0001). SAA1.1/1.5 was higher in non-amyloid patients (p = 0.0069) and in controls (p = 0.0082) than in patients with amyloidosis. Bivariate logistic regression revealed an increased risk of AA amyloidosis with three genotypes, SAA1.1/1.1 [odds ratio 7.589 (OR); 95% confidence interval (CI): 2.130-27.041] (p = 0.0018), SAA1.1/1.3 [OR 5.700; 95% CI: 1.435-22.644] (p = 0.0134), and M694I/M694I [OR 4.6; 95% CI: 1.400-15.117] (p = 0.0119). The SAA1.1/1.5 genotype [OR 0.152; 95% CI: 0.040-0.587] (p = 0.0062) was protective against amyloidosis. In all groups, the - 13 C/C genotype predominated, and was not related to renal complication [OR 0.88; 95% CI: 0.07-10.43] (p = 0.915). In conclusion, in contrast to the - 13 C/T polymorphism, the SAA1.1/1.1, SAA1.1/1.3 and M694I/M694I genotypes may increase the risk of developing renal AA amyloidosis in the Algerian population.

The M694I/M694I genotype: A genetic risk factor of AA-amyloidosis in a group of Algerian patients with familial Mediterranean fever.

Familial Mediterranean fever (FMF, OMIM 249100) is the most common hereditary fever, resulting from mutations in MEFV. FMF is characterized by episodic febrile attacks and polyserositis. Renal AA-amyloidosis is a major complication, which often leads to end-stage renal disease in untreated patients. The data about the renal AA-amyloidosis secondary to FMF are scarce in North African countries and non-existent in Algeria. We aimed to investigate the MEFV mutations associated with this complication in an Algerian patient cohort. Molecular analysis included 28 unrelated Algerian FMF patients with ascertained amyloidosis, 23 of them were symptomatic and 5 were asymptomatic. For this study, a group of 20 FMF patients without renal amyloidosis were selected as controls according to their age, disease onset and disease duration. The mutations were detected by sequencing exon 10 of MEFV. A total of 87.5% (49/56) mutant alleles were identified in 27/28 analyzed patients; p.M694I was predominant and appeared with an allele frequency of 62.5%, followed by p.M694V (17.85%), p.M680I (5.35%) and p.I692Del (1.78%). Remarkably, only p.M694I mutation was observed among the asymptomatic patients. The M694I/M694I genotype, identified in 14/27 (52%) patients, was significantly associated with the development of amyloidosis compared to group of controls (p = 0.022). This study did not link the M694V/M694V genotype to the renal complication despite the fact that it has been observed only in the patients with amyloidosis (3/27; 11%) (p = 0.349). The association of other identified genotypes to this complication was statistically insignificant. The progression of amyloidosis led to end-stage renal disease in 14 patients with 6 deaths. This study shows that p.M694I homozygosity is a potential genetic risk factor for the development of renal AA-amyloidosis in Algerian FMF patients.