In the northernmost county of Seeden (Norrbotten) two different clinical and genetic types of hereditary palmoplantar keratoderma have been reported: a common autosomal dominant form, corresponding to the descriptions performed by Unna and Thost, and an obviously autosomal recessive form, which clinically differed from other diffuse palmoplantar keratodermas, named the Gamborg Nielsen type. For further family studies and to support its probably recessive inheritance a demographic mapping of four families with this rare keratinization disorder was performed. It could be shown that these families belonged to the same family at different levels of generations; however, a common ancestor, who connected these families was not found. Marital distance of heterozygotes and birth places of probands were limited to an area, which is generally known to harbour different inherited disorders. According to a map of the origin of family members, it was shown that the major part originated from the same area and that the integration of family members had occurred in the same places. It was concluded that adoption of a demographic database for family studies in genetic research may contribute valuable information about family relations.