Growth performance, as well as marbling, is the main breeding objective in Japanese Black
(JB) cattle, the major beef breed in Japan. The septin 7 (CDC10) gene, involved in cellular
proliferation, is located within a genomic region of a quantitative trait locus for growthrelated
traits. In this study, we first showed that the expression levels of the CDC10 gene in
the skeletal muscle were higher in JB steers with extremely high growth performance than
in JB steers with extremely low growth, using real-time PCR. Further, a single nucleotide
polymorphism (SNP), NC_007302.5:g.63264949G>C, was detected in the promoter region
of the CDC10 gene and genotyped in three Japanese cattle breeds (known as ‘Wagyu’ in
Japan) and the Brown Swiss dairy cattle breed. All four cattle populations showed a
moderate genetic diversity at the SNP of the CDC10 gene. An association analysis indicated
that the SNP was associated with growth-related traits in JB cattle. These findings suggest
possible effects of the expression levels in the skeletal muscle and the SNP of the CDC10 gene
on growth-related traits in JB cattle. The CDC10 SNP may be useful for effective markerassisted
selection to increase beef productivity in JB beef cattle.