In other species: rock pigeon , chicken , turkey , dog , domestic cat , pig , Arabian camel , guanaco , llama , Western roe deer , taurine cattle , goat , sheep , domestic guinea pig , alpaca , springbok

Categories: Skeleton phene (incl. short stature & teeth) , Limbs / fins / digit / tail phene

Links to possible relevant human trait(s) and/or gene(s) in OMIM: 174500 (trait) , 605522 (gene) , 188740 (trait)

Single-gene trait/disorder: yes

Mode of inheritance: Autosomal dominant

Disease-related: yes

Key variant known: no

Year key variant first reported: 2024

Key variant is published: no

Cross-species summary: Often called preaxial polydactyly (PPD)

Inheritance: Baville et al. (2024) reported 9 Berber / Arabian-Berber horses with non-syndromic polydactyly: "All nine affected horses were related to a single stallion. Pedigree analysis revealed that the most likely inheritance pattern was autosomal dominant with incomplete penetrance and variable expressivity."

Molecular basis: Luan et al. (2024) identified a "missense variant [EquCab3.0 chr4:g.107353368A>G] (rs1138485164) in the 3rd exon of LMBR1" as likely causal variant for polydactyly in a paternal half-sib family [of Yili horses] with 3 affected animals and confirmed via gene editing "that the variant down-regulates LMBR1expression, increases the proliferative viability of mutant cells, and inhibits apoptosis. This study suggests that LMBR1 might play a role in the development of polydactyly and that the variant detected in this study is related to polydactyly in horses. However, further research is needed to determine whether a direct relationship exists."  The variant was not present in 100 normal horses from different breeds investigated in this study, but has been identified in other studies based on information linked to the European variation archieve identifier rs1138485164.

Breeds: Barb (Horse) (VBO_0000912), West African Barb (Horse) (VBO_0001092), Yili (Horse) (VBO_0017454).
Breeds in which the phene has been documented. (If a likely causal variant has been documented for the phene, see the variant table breeds in which the variant has been reported).

Associated gene: