Yoshiaki Kikkawa

By Yuta Seki, Kenta Wada and Yoshiaki Kikkawa

To date, the genetic loci associated with disease and economic traits have been identified in livestock based on linkage analysis or genome-wide association studies. These analyses require the use of numerous genetic markers, of which microsatellites have been utilized most extensively because they allow for the easy genotyping of allelic variation at each locus using PCR. In the domestic goat (Capra hircus), microsatellite markers are powerful tools for various genetic studies, such as the estimation of intra- and interpopulation genetic diversity, linkage analyses of phenotypic traits, and marker-assisted selection of favorable phenotypes; however, the studies on goats are less extensive than those on other major livestock. The aim of this chapter is to summarize the currently available information on goat breeding using microsatellite markers. In particular, we use various studies, including our own recent work, to illustrate how these markers may be used to identify phenotypic traits.

Part of the book: Microsatellite Markers

By Shumpei P. Yasuda, Yuki Miyasaka and Yoshiaki Kikkawa

Acquired hearing loss, which includes age-related hearing loss and noise-induced hearing loss, is a common hearing impairment and shows phenotypic variability. One reason for phenotypic variability is influence of genetic background. The modifiers underlying genetic background are modulated and advance the hearing phenotypes through gene-gene interactions with other etiological genetic factors. Moreover, the modifiers play a role in the susceptibility of environmental hearing risk factors, namely, the strength and weakness of environmental susceptibility often modulate and advance hearing phenotypes via gene-environment interactions. The complicated gene-gene and gene-environment interactions make genetic analysis of acquired hearing loss difficult. In particular, the effects of environmental factors cannot be completely excluded or controlled. Although genome-wide approaches to identify genetic modifiers have proven challenging in humans, the responsible genes and mutations are widely unknown. In this chapter, we suggest that mouse models are useful for studying genetic background effects for acquired hearing loss. The genetic analysis of mouse models identified the genetic modifiers. We review the genetic research in mouse models for acquired hearing loss to identify and confirm the modifiers by both forward and reverse genetics approaches.

Part of the book: An Excursus into Hearing Loss