The mouse curly whiskers () mutations are recessive alleles of hephaestin-like 1 ().

The spontaneous, curly whiskers mutation (abbreviated ) generates kinky, brittle vibrissae in homozygous mice. Although has been mapped to the centromeric end of mouse Chromosome 9, no particular gene has been causally implicated, and this lack of genetic assignment has stymied 's complete molecular and functional analysis. As a foundation for its positional cloning, we have fine-mapped to a small, 0.57 Mb interval that contains only three skin-expressed genes, including hephaestin-like 1 (), which encodes a membrane-bound, multi-copper ferroxidase. Sequence analysis of all coding regions in / mutants revealed a single-base-pair substitution that alters mRNA splicing, and is specific to the allele, only. Sequence analysis of a second, independent, re-mutation to curly whiskers (that we verified by complementation testing with and have designated ) revealed a distinct defect in (a frame-shifting, single-base-pair insertion) that is specific to . The results presented strongly suggest that defects in the gene are the molecular basis of the classical, curly-whiskers mutant phenotypes.