title: Characterization of a highly polymorphic marker adjacent to the SLC4A1 gene and of kidney immunostaining in a family with distal renal tubular acidosis.
abstract: BACKGROUND
  Mutations in the human SLC4A1 (AE1/band 3) gene are associated with hereditary spherocytic anaemia and with distal renal tubular acidosis (dRTA). The molecular diagnosis of AE1 mutations has been complicated by the absence of highly polymorphic genetic markers, and the pathogenic mechanisms of some dRTA-associated AE1 mutations remain unclear. Here, we characterized a polymorphic dinucleotide repeat close to the human AE1 gene and performed an immunocytochemical study of kidney tissue from a patient with inherited dRTA with a defined AE1 mutation.
  
  
  METHODS
  One CA repeat region was identified in a phage P1-derived artificial chromosome (PAC) clone containing most of the human AE1 gene and the upstream flanking region. We determined its heterozygosity value in multiple populations by PCR analysis. Genotyping of one family with dominant dRTA identified the AE1 R589H mutation, and family member genotypes were compared with the CA repeat length. AE1 and vH(+)-ATPase polypeptides in kidney tissue from an AE1 R589H patient were examined by immunocytochemistry for the first time.
  
  
  RESULTS
  This CA repeat, previously reported as D17S1183, is approximately 90 kb upstream of the AE1 gene and displayed considerable length polymorphism, with small racial differences, and a heterozygosity value of 0.56. The allele-specific length of this repeat confirmed co-segregation of the AE1 R589H mutation with the disease phenotype in a family with dominant dRTA. Immunostaining of the kidney cortex from one affected member with superimposed chronic pyelonephritis revealed vH(+)-ATPase-positive intercalated cells in which AE1 was undetectable, and proximal tubular epithelial cells with apparently enhanced apical vH(+)-ATPase staining.
  
  
  CONCLUSIONS
  The highly polymorphic dinucleotide repeat adjacent to the human AE1 gene may be useful for future studies of disease association and haplotype analysis. Intercalated cells persist in the end-stage kidney of a patient with familial autosomal dominant dRTA associated with the AE1 R589H mutation. The absence of detectable AE1 polypeptide in those intercalated cells supports the genetic prediction that the AE1 R589H mutation indeed causes dominant dRTA.
authors.affiliation: Molecular Medicine Unit, Beth Israel Deaconess Medical Center, Boston, MA 02115, USA.
authors.forename: Chairat
authors.initials: C
authors.lastname: Shayakul
authors.forename: Petr
authors.initials: P
authors.lastname: Jarolim
authors.forename: Marie
authors.initials: M
authors.lastname: Zachlederova
authors.forename: Daniel
authors.initials: D
authors.lastname: Prabakaran
authors.forename: Dionisio
authors.initials: D
authors.lastname: Cortez-Campeao
authors.forename: Dana
authors.initials: D
authors.lastname: Kalabova
authors.forename: Alan K
authors.initials: AK
authors.lastname: Stuart-Tilley
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Ideguchi
authors.forename: Christlieb
authors.initials: C
authors.lastname: Haller
authors.forename: Seth L
authors.initials: SL
authors.lastname: Alper
mesh_terms: D000141:Acidosis, Renal Tubular / Q000453:epidemiology / Q000235:genetics* / Q000473:pathology*; D001457:Anion Exchange Protein 1, Erythrocyte / Q000235:genetics*; D016022:Case-Control Studies; D015331:Cohort Studies; D005260:Female; D005786:Gene Expression Regulation; D005799:Genes, Dominant; D005819:Genetic Markers / Q000235:genetics; D020022:Genetic Predisposition to Disease; D005820:Genetic Testing; D006801:Humans; D015994:Incidence; D008297:Male; D009154:Mutation; D010375:Pedigree; D011110:Polymorphism, Genetic; D012016:Reference Values; D012680:Sensitivity and Specificity
chemical_list: D001457:Anion Exchange Protein 1, Erythrocyte; D005819:Genetic Markers