title: Expression of a novel missense mutation found in the A4GALT gene of Amish individuals with the p phenotype.
abstract: BACKGROUND
  The rare p phenotype is found at a higher frequency in Amish people than in other populations. Different mutations in the 4-alpha-galactosyltransferase gene (A4GALT), responsible for synthesis of P(k) (Gb(3)) antigen, have been found to cause the P(k)-deficient p phenotype. The aim of this study was to explore the molecular background of the p phenotype in people of Amish origin.
  
  
  METHODS
  Twenty blood samples with the p phenotype, 19 of them from Amish individuals and 1 Pakistani, were investigated. Amplification of genomic DNA by polymerase chain reaction (PCR) and sequencing by capillary electrophoresis were performed. Blood donors of different geographic origin were screened with PCR-allele-specific primer to investigate whether the novel mutation occurs among individuals with common phenotypes. The mutation was also cloned into an expression vector and transfected to Namalwa cells, which do not normally express P(k). P(k) expression on the transfected cells and P/P(k) on red blood cells (RBCs), both with p and with common phenotypes, were analyzed by flow cytometry.
  
  
  RESULTS
  All 20 samples were homozygous for 299C>T changing serine to leucine in a region that is highly conserved in homologous genes across species borders. The mutation was not found in any of the 500 alleles of blood donors investigated. P(k) expression was neither observed by serology and flow cytometry on p RBCs from Amish individuals nor following transfection of cells with constructs containing the novel missense mutation.
  
  
  CONCLUSIONS
  A novel A4GALT missense mutation causes the p phenotype in Amish individuals.
authors: Lund University Hospital Blood Center, Lund, Sweden.
authors: Asa
authors: A
authors: Hellberg
authors: Anne-Christine
authors: AC
authors: Schmidt-Melbye
authors: Marion E
authors: ME
authors: Reid
authors: Martin L
authors: ML
authors: Olsson
mesh_terms: D000483:Alleles; D015295:Antigens, Tumor-Associated, Carbohydrate / Q000096:biosynthesis; D001483:Base Sequence; D004252:DNA Mutational Analysis; D005006:Ethnicity / Q000235:genetics*; D005434:Flow Cytometry; D005700:Galactosyltransferases / Q000235:genetics* / Q000378:metabolism; D005838:Genotype; D006801:Humans; D020125:Mutation, Missense; D010641:Phenotype; D016133:Polymerase Chain Reaction
chemical_list: D015295:Antigens, Tumor-Associated, Carbohydrate; C472766:Gb3 antigen; D005700:Galactosyltransferases