In other species: dog , domestic cat , horse , pig , taurine cattle , goat , rabbit

Categories: Vision / eye phene

Mendelian trait/disorder: no

Mode of inheritance: Multifactorial

Disease-related: yes

Key variant known: no

Cross-species summary: Inversion (turning inward) of the margin of the eyelid.

Mapping: From a GWAS on "998 Columbia, Polypay, and Rambouillet sheep [each] genotyped with 50,000 SNP markers", Mousel et al. (2015) identified strong associations in SLC2A9 (GLUT9) on chromosome OVA6 and near NLN on chromosome OVA16. Hirter et al. (2020):"A GWAS using 150 SWA [Swiss White Alpine] sheep (90 affected lambs and 60 controls), based on 600k SNP data, revealed a genome‐wide significant signal on chromosome 15. The 0.2 Mb associated region contains functional candidate genes, SMTNL1 and CTNND1. Pathogenic variants in human CTNND1 cause blepharocheilodontic syndrome 2, a rare disorder including eyelid anomalies, and SMTNL1 regulates contraction and relaxation of skeletal and smooth muscle. WGS of a single entropion‐affected lamb revealed two private missense variants in SMTNL1 and CTNND1. . . . Subsequent genotyping of both variants in 231 phenotyped SWA sheep [discounted both variants, leading the authors to] "propose that these protein‐changing variants are unlikely to explain the phenotype . . . [and to] conclude that entropion represents a more complex disease caused by different non‐coding regulatory variants".