Dermatoglyphics (from ancient Greek derma=skin, glyph=carving) is the scientific study of fingerprints, lines, mounts, and shapes of hands. Dermatoglyphics refers to the formation of naturally occurring ridges on certain body parts, namely palms, fingers, soles and toes. These are areas where hair usually does not grow and these ridges allow for increased leverage when picking up objects or walking barefoot. The finger prints of both hands are not the same. They do not change size or shape throughout a person's life, except in cases of serious injuries that scar the dermis. As a term, dermatoglyphics is used to distinguish it from the superficially similar pseudoscience of palmistry. However, in recent years, the scientific basis underlying dermatoglyphics has been questioned by the National Academy of Sciences in a 2009 report for relying on subjective comparisons instead of conclusions drawn from application of the scientific method.
Dermatoglyphic and Genetic Aberrations
Dermatoglyphics which are correlated with genetic abnormalities are useful in diagnoses of these disorders at birth or soon after. They are used in the diagnosis of congenital malformations.
Klinefelter's syndrome: Excess of arches on digit 1, more frequent ulnar loops on digit 2, overall fewer whorls, lower ridge counts for loops and whorls as compared with controls, and significant reduction of the total finger ridge count.
Cri du chat (5p-): Excess of arches on fingertips and single transverse palmar creases in 90%.
Congenital blindness: Initial data points to abnormal triradius and excess of arches on fingertips.
Naegeli–Franceschetti–Jadassohn syndrome: patients lack dermatoglyphics of any kind.
Noonan syndrome: Increased frequency of whorls on fingertips, and the axial triradius t, as in Turner syndrome, is more often in position t' or t" than in controls. Increased incidence of the single transverse palmar crease.
Trisomy 13 (Patau syndrome): Excess of arches on fingertips and single transverse palmar creases in 60%.
Trisomy 18 (Edward's syndrome): 6 - 10 arches on fingertips and single transverse palmar creases in 30%.
Trisomy 21 (Down syndrome): People with Down syndrome have a finger print pattern with mainly ulnar loops, and a significantly different angle between the triradia a, t and d (the 'adt angle'). Other differences often include a single transverse palmar crease ("Simian line") (in 50%), and patterns in the hypothenar and interdigital areas, lower ridge counts along digital midlines, especially in little fingers, which corresponds to finger shortening in those with Down syndrome. There is less variation in dermatoglyphic patterns between people with Down syndrome than between controls, and dermatoglyphic patterns can be used to determine correlations with congenital heart defects in individuals with Down syndrome by examining the left hand digit ridge count minus the right hand digit ridge count, and the number of ridges on the fifth digit of the left hand.
Turner syndrome: Predominance of whorls, although the pattern frequency depends on the particular chromosomal abnormality.
Rubinstein-Taybi Syndrome: preponderance of broad thumbs, low mean ridge count, and fingerprint patterns occurring on interdigital areas.
Schizophrenia: A-B ridge counts are generally lower than in controls.