Simian Line Forum

A member recently posted that people who have Down Syndrome may also have two bones rather than 3 in the little finger. So far I have been unable to find confirmation of this. Is this another feature used to diagnose Downs? Is it also caused by the extra chromosome 21?

See http://www.emedicine.com/derm/topic687.htm
"broad, short hands, feet, and digits; short curved fifth finger (dysplasia of the mid phalanx), clinodactyly of the fifth finger"

I think descriptions of little fingers reference back to an article that I can't easily access:
Clinical aspects of down syndrome from infancy to adulthood
American Journal of Medical Genetics
Volume 37, Issue S2, Date: 1990, Pages: 52-56
Siegfried M. Pueschel

I think it has been proposed that this might be used in diagnosis but I don't know what the terms mean- "hallucal and forefinger pattern, and palmar triradius".

J Pediatr. 1982 Jun;100(6):903-6. A diagnostic index for Down syndrome. Rex AP, Preus M.

from Abstract: We have made use of eight phenotypic findings of Down syndrome to develop an effective diagnostic index. We estimate that about 95% of patients who are suspected of having the syndrome can be categorized as having or not having it with 99.9% confidence. .....The eight features used in the index include three dermatoglyphic traits (hallucal and forefinger pattern, and palmar triradius), two measurements of physical traits (ear length and internipple distance), and three other clinical findings (Brushfield spots, wide-spaced first toe, and excess back neck skin).