Hereditary nasal parakeratosis (HNPK) is an inherited disorder described in Labrador Retrievers and Greyhounds. It has been associated with breed-specific variants in the SUV39H2 gene encoding a histone methyltransferase. The disorder is characterized by abnormal keratinocyte differentiation in the nasal mucosa, leading to the formation of parakeratotic cells. This condition highlights the importance of histone modification in regulating keratinocyte differentiation and the potential for breed-specific genetic variants to influence disease susceptibility.