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QTL on mouse chromosomes 1 and 4 causing sperm-head morphological abnormality and male subfertility

Hideo Gotoh1, Keitaro Hirawatari, Naoto Hanzawa

  • 1Agrogenomics Research Center, National Institute of Agrobiological Sciences, Tsukuba, Ibaraki, Japan. gotoh@affrc.go.jp

Mammalian Genome : Official Journal of the International Mammalian Genome Society
|March 23, 2012
PubMed

Insights

Researchers identified two genes on mouse chromosomes 1 and 4 that cause high rates of sperm-head abnormalities, leading to male subfertility. The major gene on chromosome 1, named Shm1, controls the abnormalities, while the Shm2 gene on chromosome 4 enhances them.

Area of Science:

  • Genetics
  • Reproductive Biology
  • Mammalian Genetics

Background:

  • The B10.M mouse strain exhibits male subfertility, characterized by a high incidence of sperm-head morphological abnormalities (44.7 ± 2.4%).
  • Previous research indicated that this phenotype results from two recessive genetic loci.

Purpose of the Study:

  • To map the specific genetic loci responsible for the high frequency of sperm-head morphological abnormalities in the B10.M mouse strain.
  • To elucidate the genetic architecture and interaction of these loci.

Main Methods:

  • Quantitative trait loci (QTL) analysis was performed on F2 intercross animals derived from B10.M and C3H mouse crosses.
  • Genome-wide mapping was conducted using 178 F2 animals, followed by fine-mapping with 854 F2 animals.

Main Results:

  • Two recessive loci were identified: a major locus on Chromosome (Chr) 1 (LOD score = 30.585) and a modifier locus on Chr 4 (LOD score = 4.532).
  • The Chr 1 locus (Sperm-head morphology 1, Shm1) was mapped between Ercc5 and D1Mit528.
  • The Chr 4 locus (Sperm-head morphology 2, Shm2) was mapped between D4Mit148 and D4Mit170.
  • The two loci exhibit non-independent effects; Shm2 enhances abnormalities only when Shm1 is homozygous for the B10.M allele.

Conclusions:

  • The genetic basis of sperm-head morphological abnormalities in the B10.M strain involves two interacting loci, Shm1 and Shm2.
  • Shm1 is the primary determinant of sperm defects, while Shm2 acts as a modifier, influencing the severity of the phenotype.
  • These findings provide a foundation for understanding the genetic control of sperm morphology and male fertility.

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