Dermatoglyphics

Dermatoglyphics (from ancient Greek derma = "skin", glyph = "carving") is the scientific study of fingerprints. The term was coined by Dr. Harold Cummins, the father of fingerprint analysis. All primates have ridged skin, and it can also be found on the paws of certain mammals and on the tails of some monkey species. In humans, dermatoglyphs are present on fingers, palms, toes, and soles, and give insight into a critical period of embryogenesis, between 4 weeks and 5 months, when the architecture of the major organ systems is developing.

Genetic disorders
Unusual dermatoglyphic patterns often relate to genetic disorders. One study of foetuses with chromosomal abnormalities showed that the dermatoglyphic patterns were delayed by more than two weeks.


 * Trisomy 21 (Down syndrome): People with Down syndrome have 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's 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.
 * 47, XXY (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.
 * 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%.
 * Cri du chat (5p-): Excess of arches on fingertips and single transverse palmar creases in 90%.
 * 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.

Trivia
Dermatoglyphics, misconjugatedly and uncopyrightable are the longest English words with no repeated letters.