All known human H1 histone genes except the H1(0) gene are clustered on chromosome 6.

PCR analysis of chromosomal DNA from a panel of human-rodent somatic cell hybrids revealed that the five human H1 histone genes H1.1 to H1.5 and the gene encoding the testis-specific H1t subtype, all of which form clusters with core histone genes, are located on chromosome 6. The H1(0) subtype, which is not neighbored by core histone genes, maps to chromosome 22. Fluorescence in situ hybridization with human metaphase chromosomes and PCR analysis of somatic cell hybrid DNA carrying only fragments of chromosome 6 revealed the region 6p21.1 to 6p22.2 as the histone gene cluster region.