Mapping Data

Experiment

• Experiment
  TEXT-QTL
• Chromosome
  7
• Reference
  J:237444 Suto J, Genetic analysis of litter size in mice. J Vet Med Sci. 2015 Mar;77(3):353-8
• ID
  MGI:5896621

Genes

Gene
Litsq2
D7Mit228

Notes

• Experiment
  The number of pups, or litter size, is a representative reproductive quantitative trait in female animals. In the current study C57BL/6J (B6) female mice were crossed with RR/SgnRbrc (RR) male mice. F1 females were then backcrossed with RR males. Backcrossed mice were weaned at 4 weeks of age and at 8-10 weeks were mated. The number of newborn offspring was scored once a day. The number of total newborn pups (TNB), the number of pups born alive (NBA) and the number of stillbirths (NSB) were recorded.
  
  Genomic DNA isolation and genotyping of microsatellite markers was performed. QTL analysis was conducted using R/qtl version 1.33-7. Threshold logarithm of odds (LOD) scores for suggestive (p<0.63) and significant (p<0.05) linkages were determined by performing 1,000 permutations for each trait.
  
  One hundred and sixty five (C57BL/6J x RR/SgnRbrc)F1 x RR/SgnRbrc backcrossed mice that had extreme phenotypes with regard to litter size were initially genotyped. Once suggestive linkages were identified for a trait the remaining 90 backcrossed mice were genotyped for all markers on relevant chromosomes.
  
  Table 1:
  
  One significant QTL was identified for total newborn pups. QTL Litsq2 (litter size QTL 2) mapped to Chromosome 7 with a LOD score of 2.67 nearest peak marker D7Mit228 (27.0 cM). The 95% confidence interval spanned between 3-36 cM. The B6 allele was the high allele, associated with increased litter sizes. Candidate genes mapping within the 95% confidence interval concerned with embryonic viability were Ppp5c, Ceacam10 and Egln2. Four suggestive alleles for litter size were identified on Chromosomes 3, 5, 10 and 13.
  
  For the number of pups born alive (NBA) four suggestive QTL were identified on Chromosomes 3, 7, 10, and 13. Plots for both traits, TNB and NBA, were very similar; QTL Litsq2 and the suggestive QTL on Chr 7 for NBA may be the same locus. The RR/SgnRbrc allele was associated with a smaller litter size for all loci.
  
  Thirty nine litters were analyyzed for stillbirths (NSB). Two suggestive QTL were identified on Chromosomes 1 and 4. At both loci the RR allele was associated with an increase in NSB.