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. Although it is found more frequently in persons with several abnormal medical conditions, it is not predictive of any of these conditions since it is also found in persons with no abnormal medical conditions.
This crease is estimated to occur in 1.5-3% of the general population, although it is more common in East Asian and Native American populations.
Former name
Because it resembles the usual condition of non-human simians, it was, in the past, called the simian crease or simian line. These terms have widely fallen out of favor due to their pejorative connotation.
Medical significance
This crease is found in 45% of people with Down syndrome. A unilateral single palmar crease was also reported in a case of chromosome 9 mutation causing nevoid basal cell carcinoma syndrome and Robinow syndrome. It is also sometimes found on the hands of the affected side of patients with Poland syndrome and craniosynostosis.
A 1971 study refutes the hypothesis that the phenomenon is caused by fetal hand movement: the appearance of the crease occurs around the second month of gestation before the digital movement phase in the womb begins.
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File:Single transverse palmar crease adult.jpg|Single transverse palmar crease in an adult
File:Normal creases adult.jpg|More common palmar creases in adults
File:Bilateral single transverse palmar crease.jpg|Bilateral single transverse palmar crease. The single transverse palmar crease is present on both hands of the individual.
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See also
- Dermatoglyphics