Amyloid : the international journal of experimental and clinical investigation : the official journal of the International Society of Amyloidosis
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Report of five rare or previously unknown amyloidogenic transthyretin mutations disclosed in Sweden.
The number of amyloidogenic transthyretin (TTR) mutations described in the literature is more than 100. However, for several mutations, the phenotype has been described in a few individuals only; thus, the knowledge of the clinical course and the outcome after therapeutical interventions such as liver transplantation is limited. We describe the phenotype associated with five rare amyloidogenic TTR mutations that lately were discovered in Sweden: ATTR Val30Leu, Ala45Ser, Leu55Gln, Gly57Arg and Tyr69His of which ATTR Gly57Arg is previously unknown. ⋯ Likewise, carpal tunnel syndrome was found or had been present in all cases except the case with the ATTR Val30Leu mutation. The phenotype of the ATTR Tyr69His mutation was characterised by oculo-meningeal symptoms with seizures and a steadily progressing dementia, symptoms rarely found in ATTR amyloidosis, but similar to those previously described for this mutation, where all cases appear to originate from one Swedish family. Two patients with the ATTR Leu55Gln and Ala45Ser mutations have been subjected to liver transplantation, but echocardiographic examination has revealed an increasing cardiomyopathy after transplantation in both cases, the ATTR Leu55Gln patient succumbed 2 years after transplantation from progressive disease.
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Serum amyloid A (SAA), a precursor of reactive amyloid deposits, is a multigene product. SAA1, predominant both as an amyloid precursor and in plasma, consists of three allelic variants (SAA1.1, SAA1.3, and SAA1.5). Several investigations have shown that the SAA1.3 allele is associated with susceptibility to AA-amyloidosis in Japanese, and the SAA1.5 allele is related with higher serum concentrations of SAA. ⋯ The affinity (kd) of SAA1.1, SAA1.3, and SAA1.5 for HDL was 1.4 x 10(-5), 1.8 x 10(-5), and 3.7 x 10(-6), respectively. rSAA1.5 showed significantly (p < 0.05) stronger affinity than the other two. The fraction of lipid-free SAA in serum was significantly (p < 0.001) lower in the patients with larger numbers of the 1.5 allele at the SAA1 locus. These results suggest that the relatively high affinity of SAA1.5 may cause the high serum concentration and may be related to the low susceptibility to amyloidosis.