TBX4 and familial clubfoot with or without associated lower limb anomalies: Previous genetic studies have identified several genes that are related to clubfoot, including PITX1, TBX4, and MYH3. The only previous genome-wide association study (GWAS) of clubfoot identified a significant single-nucleotide polymorphism (SNP) between NCOR2 and ZNF664, and there was evidence suggesting that FOXN3, SORCS1, and MMP7/TMEM123 were also associated with clubfoot [7].