title: QTL on mouse chromosomes 1 and 4 causing sperm-head morphological abnormality and male subfertility.
abstract: The B10.M mouse strain represents a model for male subfertility as it produces a significantly low number of offspring. The only known male reproductive phenotype of this strain is its high frequency of sperm-head morphological abnormalities (44.7 ± 2.4 %). We previously reported that this phenotype was the product of two recessive loci. In this study we mapped the loci causing the high frequency of sperm-head morphological abnormalities in this strain using F2 animals produced by crossing B10.M and C3H mice. Quantitative trait loci (QTL) analysis (n = 178) identified two recessive genes, one on Chromosome (Chr) 1 (LOD score = 30.585) and one on Chr 4 (LOD score = 4.532). Further analysis (n = 854) mapped the locus on Chr 1 between Ercc5 (23.55 cM) and D1Mit528 (25.95 cM) and the locus on Chr 4 between D4Mit148 (69.48 cM) and D4Mit170 (70.47 cM). It was also found that the effects of these two loci were not independent. The major locus on Chr 1 determines the expression of sperm-head abnormalities, while the locus on Chr 4 enhances the frequency of abnormalities only when the genotype of the Chr 1 locus is homozygous for the B10.M allele. The major locus on Chr 1 was named sperm-head morphology 1 (Shm1), while the modifier locus on Chr 4 was named sperm-head morphology 2 (Shm2).
authors.affiliation: Agrogenomics Research Center, National Institute of Agrobiological Sciences, Tsukuba, Ibaraki, Japan. gotoh@affrc.go.jp
authors.forename: Hideo
authors.initials: H
authors.lastname: Gotoh
authors.forename: Keitaro
authors.initials: K
authors.lastname: Hirawatari
authors.forename: Naoto
authors.initials: N
authors.lastname: Hanzawa
authors.forename: Ikuo
authors.initials: I
authors.lastname: Miura
authors.forename: Shigeharu
authors.initials: S
authors.lastname: Wakana
mesh_terms: D000818:Animals; D002874:Chromosome Mapping; D033481:Chromosomes, Mammalian / Q000235:genetics*; D005260:Female; D005838:Genotype; D007248:Infertility, Male / Q000235:genetics* / Q000473:pathology; D008126:Lod Score; D008297:Male; D051379:Mice; D008809:Mice, Inbred C3H; D008810:Mice, Inbred C57BL; D040641:Quantitative Trait Loci; D013077:Sperm Head / Q000473:pathology*; D013094:Spermatozoa / Q000002:abnormalities / Q000473:pathology