In other species: goat , sheep , rabbit

Categories: Integument (skin) phene

Links to possible relevant human trait(s) and/or gene(s) in OMIM: 608248 (gene) , 194300 (trait) , 604095 (gene) , 612630 (trait)

Single-gene trait/disorder: unknown

Mode of inheritance: Autosomal dominant

Disease-related: no

Cross-species summary: fibre diameter variation of hair/wool

Species summary: 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." See also information at  OMIA:002841-30538 : Fleece variation, TRPV3-related in Vicugna pacos

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."
Tan et al. (2026) used additional Suri and Huacaya animals in a GWAS, which strengthened the previously reported  association between differences in fleece type and a region on chromosome 16 containing several keratin genes (Tan et al. 2024). 

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 [omia.variant:1682] ... , a gene known to be involved in hair growth and cycling, thermal sensation, cold tolerance and adaptation in several species."
Tan et al. (2026) genotyped the TRPV3 variant (omia.variant:1682) reported by Palotti et al. (2024) "in 175 alpacas of both fleece types and ... found ... a genotype frequency of 0.77 for the homozygous reference genotype and 0.23 for the heterozygous genotype in Huacayas and 0.79 for the homozygous reference genotype and 0.21 for the heterozygous genotype in Suris, while no animal showed the homozygous variant genotype." The authors concluded that "a causal role of the TRPV3 variant was not supported."

Breeds: Huacaya (Alpaca) (VBO_0000039), Suri (Alpaca) (VBO_0000040).
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).