Imagine getting to immigration and struggling to get into a country, not because you don't have a passport or legal status, but because you have no fingerprints. People with adermatoglyphia, also known as 'immigration delay disease', have missing fingerprints from birth, and have reduced levels of sweat glands in their skin. Researchers now think they have isolated the genetic mutation behind this rare disorder.
The biology of the formation of fingerprints is largely unknown, so a team of scientists based at the Tel Aviv Sourasky Medical Center in Israel studied one of only four known families with this condition worldwide; a Swiss family with autosomal dominant adermatoglyphia.
By comparing nine affected and seven unaffected members of the family over three generations using linkage and haplotype analyses, the researchers found differences in 17 regions close to genes, but couldn't pinpoint a suitable candidate. After studying an online database of rare DNA transcripts, they tracked down a mutation near a short version of SMARCAD1, a little-known gene thought to be associated with skin cell folding in fetal development. The shorter version is expressed only in the skin, and the mutated DNA causes aberrant splicing, stopping the expression of SMARCAD1 in family members with adermatoglyphia.
The dermatoglyphs, or ridges on the finger tips that form the fingerprints, are normally fully formed by week 24 of pregnancy and, bar scarring and damage, do not change during a person's lifetime. While the purpose of fingerprints is not entirely clear, it has been suggested they reduce friction between fingertips and surfaces, which may improve sensitivity. They are also very useful for identification, as no two fingerprints are alike, even those of identical twins.
While this research may only account for one cause of adermatoglyphia, because abnormal fingerprints are associated with a number of severe disorders, it may have applications in a variety of diseases and in studies of human development.
This research was published this month in the American Journal of Human Genetics.