DNA markers associated with disease resistance are essential in
marker-assisted breeding for accelerating genetic improvement for
disease resistance. Single nucleotide polymorphisms (SNPs)
markers are the markers of choice for many genetic studies because
they are abundant in genomes, and can be genotyped by many
methods [10]. SNPs in immune genes may be related to the resistance
of hosts against pathogens [11e13]. However, DNA markers
associated with disease resistance were only identified in a few
aquaculture species, such as salmon [14], rainbow trout [15], Asian
seabass [16], Japanese flounder [7] and Penaeus chinesis [17].
Therefore, to perform marker-assisted breeding for disease resistance
in fish, it is essential to study more immune related candidate
genes and to examine whether the polymorphisms in these genes
are associated with disease resistance.