Is there any relation between palm creases and down's syndrome?

Common finding: It is thought that the relaxed or loose muscle tone of a Down syndrome fetus contributes to the formation of a 4 finger (rather than 3) palm crease.Although it happens in some normal kids, occurs on one or both sides in 45% of ds cases.

See below: Despite well known finding, single palmar crease is noted only in half of the proven cases of down syndrome. Individual with single crease has an 1:60 chance to be diagnosed as having down syndrome.