Categories: Integument (skin) phene

Mendelian trait/disorder: yes

Mode of inheritance: Autosomal incomplete dominant

Disease-related: no

Key variant known: yes

Year key variant first reported: 2018

Mapping: Dong et al. (2018): "Kirin, a Chinese indigenous chicken breed that originated in the Guangdong province, is famous for its frizzle feathers. The KRT75 gene is considered as the dominant gene responsible for the frizzle trait in several chicken breeds, but this is not the case in the Kirin breed. ... A resource population was produced by crossing Kirin and Huaixiang chickens to produce F1 and F2 generations. DNA samples from 75 frizzle feather and normal feather individuals were sequenced with double-digest genotyping by sequencing (dd-GBS)."

Molecular basis: Dong et al. (2018): "Sanger sequencing was used to screen for mutations in the exons of five genes of this type II α-keratin cluster. A 15-bp deletion in exon 3 of KRT75L4 that showed complete segregation with the frizzle phenotype was detected within the F2 population. Transcriptome sequencing demonstrated that KRT75L4 was expressed but that the transcript was shorter in Kirin than in Huaixiang chickens. In addition, by using Sanger sequencing, we were able to confirm that the deletion was in complete linkage with frizzle feathers." Chen et al. (2021) identified the same mutation in a different breed: "frizzle feather characteristics were observed in a local breed called Xiushui Yellow Chicken in Jiangxi, China. ... Using a comparative genome strategy and genome-wide association study, a missense mutation ... and a 15-bp deletion ... in KRT75L4 were identified ... . Based on genotyping performed in a large Xiushui Yellow Chicken population, the g.5285437-5285451delGATGCCGGCAGGACG mutation in KRT75L4 was confirmed as the putative causative mutation of frizzle feather."
Qin et al. (2024) used CRISPR/Cas9 technology to knock out KRT75L4 in chicken. This study involves genetically modified/edited organisms (GMO).  

Genetic engineering: Yes - in addition to the occurrence of natural variants, variants have been created artificially, e.g. by genetic engineering or gene editing
Have human generated variants been created, e.g. through genetic engineering and gene editing

Breeds: Kirin (Chicken) (VBO_0016879), Xiushui Yellow (Chicken) (VBO_0016878).
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: