Categories: Pigmentation phene

Links to possible relevant human trait(s) and/or gene(s) in OMIM: 609523 (gene)

Single-gene trait/disorder: yes

Mode of inheritance: Autosomal recessive

Disease-related: no

Key variant known: yes

Year key variant first reported: 2024

Species summary: Arbore et al. (2024) investigated the chemical base of plumage colour variation in parrots and identified that "ALDH3A2, which oxidizes aldehyde psittacofulvins into carboxyl forms in late-differentiating keratinocytes during feather development" influences "selective deposition of red aldehyde- and yellow carboxyl-containing psittacofulvin molecules in developing feathers." The authors used dusky lory, which naturally occur with either red or yellow pigmentation, to identify the role of ALDH3A2. 

Inheritance: Pedigree analysis from 20 breeding couples identified that yellow is dominant over red (Arbore et al., 2024)

Mapping: Arbore et al. (2024) sequenced the genomes of 35 red and 22 yellow dusky lories. Association testing identified three variants in a 284 bp interval downstream of the last exon of ALDH3A2 to be associated with the colour phenotype. Analysis of expression data from regenerating feather follicles in dusky lories and in rosy-faced lovebirds further supported that differentially expression of ALDH3A2 influences feather colour (with lower expression in red feathers).

Molecular basis: Arbore et al. (2024) propose that one of the three variants identified in the association mapping is the causal variant for the colour polymorphism in dusky lories. The variant, "(scaffold_13:6,288,712T>C), located in a non-coding region 42 bp downstream of the longest ALDH3A2 transcript, exhibited the anticipated genotypes in nearly all individuals (98%). ... The mismatched genotype in one individual may be attributable to genetic heterogeneity or epistatic interactions with unknown genetic factors located elsewhere in the genome." Further analysis identified that the variant is located in a proposed regulatory region.  

Associated gene: