Variation in the ovine trichohyalin gene and its association with wool curvature

Trichohyalin (TCHH) is a protein found in ovine wool fibres. It is part of the interfilamentous matrix protein and cross-links both to itself and to the keratin intermediate filament proteins. TCHH is also believed to play a role in the regulation of calcium levels within the hair follicle. This study used PCR-single stranded conformational polymorphism (PCR-SSCP) analysis to investigate variation in the ovine TCHH gene (TCHH). Three sequence variants (A, B and C) were detected in 210 New Zealand (NZ) Romney, Merino, Corriedale, Poll Dorset and cross-bred sheep, with frequencies of 59.0%, 36.9% and 4.1%, respectively. Two single nucleotide polymorphisms (SNPs) were identified in these variants, one located in the 3′ region of intron 2 (c.139-14) and the other one located in exon 3 (c.227). The SNP located in the exon is non-synonymous and would result in an amino acid residue change (p.76Ala/Glu). The association between variation in TCHH and wool traits was investigated in a large half-sib family, in which the sire was AB heterozygous. Progeny that inherited A produced wool with lower mean fibre curvature (MFC), than those that inherited B (P = 0.026). No effects on other wool traits were observed. These results suggest that variation in ovine TCHH affects wool curvature.