Other rare genetic syndromes that show (partial) overlap with the phenotype of Fstl1 KO mice are small patella syndrome (SPS; OMIM 147891) (see Table 3) (Offiah et al., 2002), caused by heterozygous loss‐of‐function pathogenic variants in TBX4 (OMIM 601719) (Bongers et al., 2004), and BILU (OMIM 609296) (B‐cell Immunodeficiency, Limb anomalies, and Urogenital malformations) (see Table 3) (Edery et al., 2001; Hugle et al., 2011). Here, TBX4 is linked to coxopodopatellar syndrome.