Takasuga et al. (2015): "To search for candidate causative variations for skeletal dysplasia and/or CW-3, three sires segregating the CW-3 QTL ... , three non-Q homozygous sires ... , and a Q-homozygous steer ... were subjected to targeted resequencing ... . The 3.3-Mb CW-3 region contained 910 candidate QTNs (858 SNPs and 52 indels), including four non-synonymous and five synonymous SNPs. ... . Non-synonymous SNPs were located in FGD3 ... and PTPDC1 ... . All non-synonymous SNPs showed strong association with carcass weight ... . The three non-synonymous SNPs in FGD3 showed complete linkage disequilibrium, while the linkage disequilibrium coefficient (r2) between the non-synonymous SNP in PTPDC1 and those in FGD3 was 0.907 in the GWAS population. ... the three non-synonymous SNPs in FDG3 caused loss of the start codon (ATG to ACG) and an amino acid substitution from His-171 (CAC) to Cys (TGC). Since the Kozak consensus sequence is present at the second Met of the 17th amino acid residue ... , the FGD3 variant probably produces an N-terminal 16 amino acid-truncated protein. ... the corresponding mutant protein showed reduced activity as a guanine nucleotide exchange factor for Cdc42." Sasaki et al. (2021) suggest that this variant (AC_000165.1:g.85826989_85826990dellinsTG, p.H171C in exon 2 of FGD3) was in close proximity of the JBH_8_1 haplotype region identified in their study. "However, the allele and the haplotype were not in LD with each other ... ; therefore, this variant was not a candidate for causative mutation in the JBH_8_1 haplotype region." Shibutani et al. (2023) conducted high-throughput screening of cattle variants and identified the FGD3 p.H171C (BTA8, g.85826989CA>TG) allele in Mishima cattle, but could not confirm the association with small chest width/depth reported by Takasuga et al. (2015), possibly due to small sample size of 72 Mishima cattle.
