Please help! i have a simian crease on both hands. what does this mean?

Single palmar crease: Single palm creases are believed to develop around 12 weeks gestation. Any insult to the developing fetus can produce these creases and associated neurologic defects. They are commonly associated with Down's Syndrome, other genetic defects, neurologic disorders and possibly Fetal Alcohol Syndrome. They are present in a small percent of the population with no other significant issues.