title: H63D homozygotes with hyperferritinaemia: Is this genotype, the primary cause of iron overload?
abstract: OBJECTIVE
  Hereditary haemochromatosis is a disease that affects iron metabolism and leads to iron overload. Homozygosity for the H63D mutation is associated with increased transferrin saturation (TS) and ferritin levels. Our objective was to find out if the homozygosity of H63D mutation was the primary cause of iron overload.
  
  
  METHODS
  We studied 45 H63D homozygotes (31 males and 14 females) with biochemical iron overload and/or clinical features of haemochromatosis. The simultaneous detection of 18 known HFE, TFR2 and FPN1 mutations and sequencing of the HAMP gene were performed to rule out the possible existence of genetic modifier factors related with iron overload.
  
  
  RESULTS
  Values of biochemical iron overload, measured as percentage TS and serum ferritin concentration (SF), in our H63D homozygotes were significantly higher in patients than in controls: TS 55 +/- 15% vs. 35 +/- 15% and SF 764 (645-883) microg/L vs. 115 (108-123) microg/L for patients and controls, respectively. These H63D homozygotes presented extreme hyperferritinaemia and no additional mutations in HFE, TFR2, FPN1 and HAMP genes were detected.
  
  
  CONCLUSIONS
  The lack of additional mutations in our H63D homozygotes suggests that this genotype could be the primary cause of iron overload in these patients. Despite our results, we cannot entirely discount the possibility that one or more genetic modifier factor exists, simply because we were unable to find it, although there was a precedent in the HFE gene. Genetic modifier factors have been described for C282Y mutations in the HFE gene, but at the present time they have never been reported in H63D homozygotes.
authors.affiliation: Department of Genetics, Hospital Virgen de la Salud, Toledo, Spain. cadedi@sescam.jccm.es
authors.forename: Carles
authors.initials: C
authors.lastname: de Diego
authors.forename: Sonsoles
authors.initials: S
authors.lastname: Opazo
authors.forename: Maria J
authors.initials: MJ
authors.lastname: Murga
authors.forename: Pedro
authors.initials: P
authors.lastname: Martínez-Castro
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019943:Amino Acid Substitution; D005260:Female; D005293:Ferritins / Q000097:blood*; D005838:Genotype; D006432:Hemochromatosis / Q000235:genetics*; D006720:Homozygote; D006801:Humans; D019189:Iron Metabolism Disorders / Q000235:genetics*; D019190:Iron Overload / Q000235:genetics*; D008297:Male; D008875:Middle Aged
chemical_list: D005293:Ferritins