title: Cheetahs have 4 serum amyloid a genes evolved through repeated duplication events.
abstract: Amyloid A (AA) amyloidosis is a leading cause of mortality in captive cheetahs (Acinonyx jubatus). We performed genome walking and PCR cloning and revealed that cheetahs have 4 SAA genes (provisionally named SAA1A, SAA1B, SAA3A, and SAA3B). In addition, we identified multiple nucleotide polymorphisms in the 4 SAA genes by screening 51 cheetahs. The polymorphisms defined 4, 7, 6, and 4 alleles for SAA1A, SAA3A, SAA1B, and SAA3B, respectively. Pedigree analysis of the inheritance of genotypes for the SAA genes revealed that specific combinations of alleles for the 4 SAA genes cosegregated as a unit (haplotype) in pedigrees, indicating that the 4 genes were linked on the same chromosome. Notably, cheetah SAA1A and SAA1B were highly homologous in their nucleotide sequences. Likewise, SAA3A and SAA3B genes were homologous. These observations suggested a model for the evolution of the 4 SAA genes in cheetahs in which duplication of an ancestral SAA gene first gave rise to SAA1 and SAA3. Subsequently, each gene duplicated one more time, uniquely making 4 genes in the cheetah genome. The monomorphism of the cheetah SAA1A protein might be one of the factors responsible for the high incidence of AA amyloidosis in this species.
authors: Department of Aging Biology, Institute on Aging and Adaptation, Shinshu University Graduate School of Medicine, Matsumoto 390-8621, Japan.
authors: Lei
authors: L
authors: Chen
authors: Yumi
authors: Y
authors: Une
authors: Keiichi
authors: K
authors: Higuchi
authors: Masayuki
authors: M
authors: Mori
mesh_terms: D002612:Acinonyx / Q000235:genetics*; D000483:Alleles; D000595:Amino Acid Sequence; D000686:Amyloidosis / Q000235:genetics; D000820:Animal Diseases / Q000235:genetics; D000818:Animals; D001483:Base Sequence; D019143:Evolution, Molecular; D005260:Female; D040461:Gene Components; D020440:Gene Duplication; D015870:Gene Expression; D056726:Genetic Association Studies; D008040:Genetic Linkage; D005838:Genotype; D008297:Male; D008969:Molecular Sequence Data; D009928:Organ Specificity; D010375:Pedigree; D020641:Polymorphism, Single Nucleotide; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D000685:Serum Amyloid A Protein / Q000235:genetics* / Q000378:metabolism
chemical_list: D000685:Serum Amyloid A Protein