Single transverse palmar crease



In humans, a single transverse palmar crease is a single crease that extends across the palm of the hand, formed by the fusion of the two palmar creases that people typically have. Because it resembles the usual condition of simian animals, it is also known as a simian crease, although this term has fallen out of favor due to its pejorative connotation.

Medical
The presence of a single transverse palmar crease can be a symptom of certain medical conditions such as Fetal alcohol syndrome and genetic abnormalities including Down syndrome and Noonan syndrome. However, such a crease appears in approximately 3% of the world population. Males are twice as likely as females to have this condition.