Mapping Data

Experiment

• Experiment
  TEXT-QTL
• Chromosome
  4
• Reference
  J:108418 Bolor H, et al., Detection of quantitative trait Loci causing abnormal spermatogenesis and reduced testis weight in the small testis (Smt) mutant mouse. Exp Anim. 2006 Apr;55(2):97-108
• ID
  MGI:3654120

Genes

Gene	Assay Type
Smtw1	visible phenotype
D4Mit199	PCR amplified length variant
Spmd1	visible phenotype
D4Mit9	PCR amplified length variant
Spmd2	visible phenotype
D4Mit38	PCR amplified length variant

Notes

• Experiment
  A several mutant lines displaying small testis arose from crossing the t³² mutation onto C57BL/6J and DDK genetic backgrounds (and also CBA/J in certain lines). Mutant males are infertile and display 1/3 to 1/2 the testis weight of normal males. Mutants also exhibit spermatogenesis arrest in early meiosis. Linkage analysis was performed on 221 male mice from a (Smt x Mus musculus molossinus)F2 intercross. Eighty-one microsatellite markers were used for the genome scan. Animals were phenotyped at 60 days of age.
  
  Linkage to paired testis weight mapped to 61.6 cM on mouse Chromosome 4 near D4Mit199 (LOD=6.1). This locus explains 15% of the variance and is named Smtw1 (small testis weight 1). Smt-derived alleles at Smtw1 confer reduced testis weight with an additive mode of inheritance. The Smtw1 95% confidence interval spans 16 cM. Linkage to spermatogenesis defect mapped to 39.5 cM near D4Mit9. This locus is named Spmd1 (spermatogenesis defect 1). Smt-derived alleles at Spmd1 confer increased meiotic defect (LOD=6.7) and multinuclear giant cells (LOD=5.1) with an additive or recessive mode of inheritance. Spmd1 explains 18% of the meiotic defect variance and 15% of the multinuclear giant cell variance. The Spmd1 95% confidence interval spans 18.6 cM. Apreviously identified testis weight QTL named Tsvw1 (37.8 cM) is located near Spmd1. Spmd2 (spermatogenesis defect 2) mapped to 25.8 cM near D4Mit38 in linkage to germ cell degeneration (LOD=4.3). Smt-derived alleles at Spmd2 confer increased germ cell degeneration with an additive mode of inheritance. Spmd2 explains 7% of the variance and the 95% confidence interval spans 34.3 cM. Spmd2 interacts epistatically with Spmd4 on chromosome 13. Animals homozygous for Smt-derived alleles at Spmd2 and Spmd4 exhibit significantly increased germ cell degeneration. This interaction accounts for 10.4% of the variance.
  
  Linkage to germ cell degeneration mapped to 22 cM on mouse Chromosome 7 near D7Mit112 (LOD=4.4). This locus explains 19% of the variance and is named Spmd3 (spermatogenesis defect 3). Smt-derived alleles at Spmd3 confer increased germ cell degeneration with a recessive mode of inheritance. The 95% confidence interval spans 12.7 cM.
  
  Linkage to meiotic defect (LOD=4.8) and germ cell degeneration (LOD=7.5) mapped to 38 cM on mouse Chromosome 13 near D13Mit27. This locus is named Spmd4 (spermatogenesis defect 4). Smt-derived alleles at Spmd4confer increased meiotic defect with an additive or recessive mode of inheritance and increased germ cell degeneration with an additive mode of inheritance. The 95% confidence interval spans a maximum of 26.5 cM. Spmd4 explains 13% of the meiotic defect variance and 13% of the germ cell degeneration variance. This locus interacts epistatically with Spmd2 on chromosome 4. Animals homozygous for Smt-derived alleles at Spmd2 and Spmd4 exhibit significantly increased germ cell degeneration. This interaction accounts for 10.4% of the variance.
  
  Linkage to paired testis weight mapped to 59 cM on mouse Chromosome X near DXMit132 (LOD=4.4). This locus explains 10% of the variance and is named Smtw2 (small testis weight 2). Smt-derived alleles at Smtw2 confer decreased testis weight. The 95% confidence interval spans 23.5 cM. A previously identified QTL linked to testisweight named Tsvw1 (47.5 cM) maps near Spmd3.