Mapping Data

Experiment

• Experiment
  TEXT-QTL
• Chromosome
  6
• Reference
  J:276482 Kautzman AG, et al., Genetic Control of Rod Bipolar Cell Number in the Mouse Retina. Front Neurosci. 2018;12:285
• ID
  MGI:6317041

Genes

Gene	Assay Type
Rbcn2	visible phenotype

Notes

• Experiment
  Genetic variants modulate the numbers of various retinal cell types in mice. For instance, there is minimal variation in the number of rod bipolar cells (RBCs) in two inbred strains of mice (A/J and C57BL/6J), yet their F1 offspring contain significantly more RBCs than either parental strain.
  
  To investigate the genetic source of RBC variation, the authors mapped QTL for variation in the number of RBCs across 24 genetically distinct recombinant inbred (RI)
  strains from the AXB/BXA strain-set.
  
  Simple interval mapping was conducted with the mapping module at GeneNetwork.
  
  Variation in RBC number mapped to three genomic loci, each modulating cell number in excess of one-third of the range observed across the RI strains:
  
  QTL Rbcn1 (rod bipolar cell number 1) maps to Chr 4: 132.22 - 134.32 Mb with a peak LRS score of 14.0 at 133.27 Mb. Rbcn1 showed an effect of A/J alleles correlating with an increase in RBC number.
  
  QTL Rbcn2 (rod bipolar cell number 2) maps to Chr 6: 51.21 - 56.21 Mb with a peak LRS score of 10.9 at 53.71 Mb. Rbcn2 showed an effect of A/J alleles correlating with an increase in RBC number.
  
  QTL Rbcn3 (rod bipolar cell number 3) maps to Chr 8: 94.33 - 102.13 with a peak LRS score of 12.7 at 98.23 Mb. Rbcn3 showed an effect of C57BL/6J alleles correlating with an increase in RBC number.
  
  The summed magnitude of Rbcn1-3 account for the entire range of RBC variation across the RI strains.
  
  The authors demonstrate that early postnatal expression of Rbcn2 candidate gene Ggct (gamma-glutamyl cyclotransferase) modulates bipolar cell number, and that a large structural variant in the putative Ggct promoter reduces expression of the gene.