Your hand’s palm has three large creases:
“Distal” means “away from the body.” The distal transverse palmar crease runs along the top your palm. It begins close to your little finger and ends at the base of your middle or index finger, or between them.
“Proximal” means “towards the body.” The proximal transverse palmar crease is below the distal crease and somewhat parallel to it, running from one end of your hand to the other. “Thenar” means “ball of the thumb.” The thenar transverse crease runs vertically around the base of your thumb.
If you have a single transverse palmar crease (STPC), the distal and proximal creases combine to form one transverse palmar crease. The thenar transverse crease remains the same.
An STPC used to be called a “simian crease,” but that term is no longer considered appropriate.
STPC can be useful in detecting disorders such as Down syndrome or other developmental problems. However, the presence of a STPC doesn’t necessarily mean that you have a medical condition.
An STPC develops during the first 12 weeks of the development of a fetus, or the first trimester. STPC has no known cause. The condition is common and doesn’t present any health problems for most people.
STPC can help your doctor identify a number of disorders. The most well-known disorder that’s associated with STPC is Down syndrome, according to the National Institute of Health.
Disorders that STPC or other similar palm crease patterns may help identify include:
This disorder occurs when you have an extra copy of chromosome 21. It causes intellectual disability, a characteristic facial appearance, and an increased risk of heart defects and digestive issues.
Fetal alcohol syndrome
This syndrome appears in children whose mothers drank alcohol during pregnancy. Alcohol damage may cause developmental delays and stunted growth, and children with this disorder may also have:
- heart problems
- nervous system problems
- social problems
- behavioral problems
This is an inherited genetic condition linked to your X chromosome. The syndrome affects your facial features, skeleton, and muscle development.
An STPC doesn’t typically cause any complications. In one reported case, STPC was associated with fused carpal bones in the hand. Fused carpal bones can be related to many syndromes and can lead to hand pain, a greater likelihood of hand fractures, and arthritis.
STPC by itself doesn’t cause any health problems and is common among healthy people without any disorders. If you do have it, your doctor can use it to look for other physical characteristics of various conditions. They can order more tests if you need them.