Simian lines

Is there a link between Simian line(s) or creases and behavioral problems?  I have an 8 y/o son who has a Simian crease on his left hand and he has been displaying impulse control problems and anger outbursts.  

[Kevin Kennedy, Ph.D.]

By itself, a single palmar crease is not associated with behavior problems. However, the presence of such a crease sometimes is associated with other problems having to do with development (e.g., fetal alcohol syndromw, Down's Syndrome, etc.). So the crease itself is not viewed as indicative of a problem, but it might (and I underscore the word might) have implications for other developmental issues.