A human hair cuticle ultrahigh-sulphur keratin Q (UHSK) gene (KRN1) has been mapped by Southern analysis of a somatic cell hybrid panel and by in situ hybridization. A probe containing the coding region of this gene mapped to 11pter- greater than 11q21 using the hybrid cell panel and on in situ hybridization mapped to two regions on chromosome 11: the distal part of 11p15, most likely 11p15.5, and the distal part of 11q13, most likely 11q13.5. A probe from the 3' noncoding region of KRN1 mapped to 11q13.5 indicating that this was the map location of the cloned gene. The sequence of 11p15.5 is termed KRN1-like (KRN1L). The results reveal that the cuticle UHSK gene family is clustered in the human genome.