Categories: Integument (skin) phene

Links to possible relevant human trait(s) and/or gene(s) in OMIM: 607066 (gene)

Mendelian trait/disorder: yes

Mode of inheritance: Autosomal dominant

Disease-related: no

Key variant known: yes

Year key variant first reported: 2024

Species-specific name: Suri

Species-specific description: Palotti et al. (2024): "Two phenotypes are described for alpaca, known as huacaya and suri. Huacaya fleece is characterized by compact, soft, and highly crimped fibers, while suri fleece is longer, straight, less crimped, and lustrous." 

Inheritance: Palottie et al. (2024): "Segregation studies suggested that two linked loci must simultaneously be homozygous for recessive alleles to produce the huacaya phenotype while the suri phenotype is determined by the presence of a dominant allele at either locus [Presciuttini et al., 2010]." Palottie et al. (2024) propose a domiannt mode of inheritance.

Mapping: More et al. (2023) aimed to identify "candidate genomic regions associated with fiber diameter in [Huacaya] alpacas. ... Four candidate regions with adjacent SNPs identified via two association methods of analysis are located on VPA6, VPA9, VPA29 and one chromosomally unassigned scaffold." Tan et al. (2024) mapped differences in Suri and Huacaya fleece type to "chromosome 16 (NW_021964192.1), which contains a cluster of keratin genes. A haplotype predominantly found in Suri alpacas has been identified which supports dominant inheritance. Variant filtering of nine whole-genome sequenced alpacas from both fleece types in the critical interval of 0.4 Mb did not reveal perfect segregation of either fleece type for specific variants."

Molecular basis: Palotti et al. (2024): "a premature termination codon (PTC) due to C > T substitution (p.Arg167*) was identified in FGF5 (fibroblast growth factor 5), a gene involved in the elongation of the fibre [Pallotti et al., 2018], and genome-wide studies found selection signals on this gene [Fan et al., 2020; Palotti et al., 2023]. Nevertheless, such variant was observed in both phenotypes and, although it may explain the coat differences observed between alpaca and its wild ancestor, it cannot account alone for the differences observed between suri and huacaya coats. ... The analysis of gene variant segregation with the suri phenotype, coupled with the filtering of gene variants present in the wild species, disclosed the presence in all the suri samples of a premature termination codon (PTC) in TRPV3 (transient receptor potential cation channel subfamily V member 3), a gene known to be involved in hair growth and cycling, thermal sensation, cold tolerance and adaptation in several species. ... This PTC in TRPV3, due to a G > T substitution [c.1423G>T] (p.Glu475*), results in a loss of 290 amino acids from the canonical translated protein, plausibly leading to a physiological dysfunction."

Breed: Suri (Alpaca) (VBO_0000040).
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: