Mapping Data

Experiment

• Experiment
  TEXT-QTL
• Chromosome
  7
• Reference
  J:90494 Bensaid M, et al., Multigenic control of hepatic iron loading in a murine model of hemochromatosis. Gastroenterology. 2004 May;126(5):1400-8
• ID
  MGI:3692629

Genes

Gene	Assay Type
Hfem1	visible phenotype
D7Mit246	PCR amplified length variant
Hamp	reported elsewhere
Hamp2	reported elsewhere
Cebpa	reported elsewhere

Notes

• Experiment
  Linkage analysis was performed on 276 phenotypically extreme Hfe< tm1Gfn> knockout animals from a (C57BL/6-Hfe^tm1Gfn x DBA/2-Hfe< tm1Gfn>)F2 intercross to identify loci associated with susceptibility to iron loading, a subphenotype of hereditary hemochromatosis. Genome scan was performed using 145 microsatellite markers spaced 10 cM - 20 cM apart. Liver iron content was analyzed at 7 weeks of age. Parental strain C57BL/6-Hfe< tm1Gfn> displays significantly higher liver iron content compared to parentalstrain DBA/2-Hfe< tm1Gfn>.
  
  Significant linkage to liver iron content mapped to 16 cM on mouse Chromosome 7 near D7Mit246 (LOD=14.46). This locus explains9.6% of the variance and is named Hfem1 (Hfe modifier 1). DBA/2-derived alleles at Hfem1 confer decreased liver iron with an additive mode of inheritance. Potential candidate genes near this region include Hamp1 (11 cM), Hamp2 (11 cM), and Cebpa (12 cM). Sequence analysis of DBA/2 and C57BL/6 genes revealed 3 amino acid substitutions in Hamp1 and 1 amino acid substitution in Hamp2. Cebpa may influence Hamp1 and Hamp2 expression in response to iron status.
  
  Significant linkage to liver iron content mapped to 49 cM on mouse Chromosome 8 near D8Mit211 (LOD=12.63). This locus explains 8.3% of the variance and is named Hfem2 (Hfe modifier 2). DBA/2-derived alleles at Hfem2 confer increased liver iron content with additive inheritance. Potential candidate genes near Hfem2 include Hmox1 (35 cM), Calr (37 cM), Mt1 (45 cM), Mt2 (45 cM), and Hp (55 cM). A duplication mutation in the Hp gene has known association with iron metabolism in humans.
  
  Hfem3 (Hfe modifier 3) mapped to 29 cM on mouse Chromosome 11 near D11Mit86 (LOD=5.85). This locus explains 5.3% of the variance. DBA/2-derived alleles at Hfem3 confer increased liver iron content with additive or recessive inheritance. Leap2 is a potential candidate gene for Hfem3.
  
  Hfem4 (Hfe modifier 4) mapped to 38 cM on mouse Chromosome 12 near D12Mit158 (LOD=6.32). This locus explains 4.6% of the variance. DBA/2-derived alleles at Hfem4 confer increased liver iron with additive or dominant inheritance.
  
  Suggestive linkage to liver iron content mapped to 12 cM on mouse Chromosome 1 near D1Mit231 (LOD=2.89). DBA/2-derived alleles at D1Mit231 confer decreased liver iron content with recessive inheritance. Authors report Slc39a1 as a candidate gene for the D1Mit231 locus but this gene is located on mouse Chromosome 3 according to mapping data found in the Mouse Genome Database. A second suggestive locus on chromosome 1 was detected at D1Mit206 (LOD=2.48). DBA/2-derived alleles at D1Mit206 confer increased liver iron content with recessive inheritance. Suggestive linkage to liver iron content also mapped to 80.2 cM on mouse Chromosome 3 near D3Mit32 (LOD=2.82). DBA/2-derived alleles at D3Mit32 confer increased liver iron content with additive inheritance.