In other species: Mexican tetra , chicken , dog , domestic cat , domestic horse , llama , taurine cattle , snow leopard

Categories: Vision / eye phene

Links to possible relevant human trait(s) and/or gene(s) in OMIM: 120200 (trait) , 120300 (trait) , 120330 (trait) , 120400 (trait) , 120430 (trait) , 120433 (trait) , 216800 (trait) , 216820 (trait) , 243910 (trait) , 608944 (gene)

Single-gene trait/disorder: unknown

Disease-related: yes

Cross-species summary: Colobomas are congenital eye abnormalities where normal tissue in or around the eye are missing.

Species summary: Zhang et al. (2025): "The Huoyan goose is a renowned indigenous Chinese goose breed, characterized by colobomus eyelid present from birth." The trait is sex-linked and of interest in developping autosexing in geese.

Inheritance: Zhang et al. (2025): "the phenotype of colobomus eyelid may be resulted from the interaction of genes at the H and M loci. The H locus is located on the Z chromosome and the M locus is located on the autochromosome. When the recessive allele at the H locus is homozygous recessive (hh), coloboma will present in the upper eyelids, while when the M locus is recessive homozygous, the function of the H locus is inhibited and the eyelid becomes normal (Yu et al., 2017). A growing body of evidence suggests that the FREM1 (FRAS1-related extracellular matrix 1) gene, located on the Z chromosome, corresponds to the H locus (Xiao et al., 2024)."

Mapping: Wen et al. (2023): "Using selective sweep analysis, we found that PTPRM on chromosome Z influences the upper eyelid coloboma phenotype of the Huoyan goose."

Markers: Zhang et al. (2025) investigated FREM1 as a candidate gene for the colobomus eyelid in Huoyan geese and identified two SNP with regulatory impact on expression (c.-385A>T;  c.-714A>G).  The authors "performed MAS using SNP2 [c.-385A>T] in the upstream regulatory region of FREM1 transcript 1 (which showed the strongest association with the colobomus eyelid trait) and the previously reported c.2625C>T SNP in the PTPRM gene ... . The results demonstrated that this MAS approach achieved 97 % rate of colobomus eyelid in progeny". The authors concluded that "that these marker loci may not be completely causative mutation loci, or there are other genes involved in the formation of the colobomus eyelid phenotype" but that their study supported "FREM1 and PTPRM as causative genes for the colobomus eyelid trait in geese ... ."

Breed: Huoyane, China (Goose (domestic)) (VBO_0009989).
Breeds in which the phene or likely causal variants have been documented. If a likely causal variant has been documented, see variant-specific breed information in the variant table. (Breed information may be incomplete).

Associated genes: