Fragile X families in a northern Swedish county: a genealogical study of possibly affected individuals in the nineteenth century

Most studies of fragile X fra(X)] families are able to document mental impairment only by family history. Using Swedish historical archives and the unique parish catechetical meeting records it is possible to document qualitative phenomena such as literacy for over 100 years. In this way it was possible to identify 7 individuals with mental retardation living in the nineteenth century in an earlier published fra(X) pedigree. Four of them were female. At the present time another 4 severely mentally retarded females with the fra(X) syndrome have been diagnosed in this family. The high prevalence of mentally retarded females might indicate a variant form of the fra(X) syndrome in this family.