Simian crease
Transverse palmar crease; Palmar crease; Simian crease
A single palmar crease is a single line that runs across the palm of the hand. People most often have 3 creases in their palms.
The crease is most often referred to as a single palmar crease. The older term "simian crease" is not used much anymore, since it tends to have a negative meaning (the word "simian" refers to a monkey or ape).
There are typically two creases in the palm, but in some people, only one crease is present. A single palmar crease occurs in about 1 out of 30 people, but is also frequently associated with other conditions such as Down syndrome, Aarskog syndrome or fetal alcohol syndrome.
Considerations
Distinct lines that form creases appear on the palms of the hands and soles of the feet. The palm has 3 of these creases in most cases. But sometimes, the creases join to form just one.
Palmar creases develop while a baby is growing in the womb, most often by the 12th week of gestation.
A single palmar crease appears in about 1 out of 30 people. Males are twice as likely as females to have this condition. Some single palmar creases may indicate problems with development and be linked with certain disorders.
Causes
Having a single palmar crease is often normal. However, it may also be associated with various conditions that affect a person's mental and physical growth, including:
What to Expect at Your Office Visit
An infant with a single palmar crease may have other symptoms and signs that, when taken together, define a specific syndrome or condition. Diagnosis of that condition is based on a family history, medical history, and complete physical exam.
Your health care provider may ask questions such as:
- Is there a family history of Down syndrome or other disorder associated with a single palmar crease?
- Does anyone else in the family have a single palmar crease without other symptoms?
- Did the mother use alcohol while pregnant?
- What other symptoms are present?
Based on the answers to these questions, the medical history, and the results of the physical exam, further testing may be necessary.
References
Jones KL, Jones MC, del Campo M. Recognizable patterns of malformation. In: Jones KL, Jones MC, del Campo M, eds. Smith's Recognizable Patterns of Human Malformation. 8th ed. Philadelphia, PA: Elsevier; 2022:chap 1.
Knoll J, Forsyth R, Pryor S. Genetics: metabolism and dysmorphology. In: Kleinman K, Mcdaniel L, Molloy M, eds. The Harriet Lane Handbook. 22nd ed. Philadelphia, PA: Elsevier; 2021:chap 13.
Slavotinek AM. Dysmorphology. In: Kliegman RM, St. Geme JW, Blum NJ, Shah SS, Tasker RC, Wilson KM, eds. Nelson Textbook of Pediatrics. 21st ed. Philadelphia, PA: Elsevier; 2020:chap 128.
Version Info
Last reviewed on: 4/25/2023
Reviewed by: Charles I. Schwartz, MD, FAAP, Clinical Assistant Professor of Pediatrics, Perelman School of Medicine at the University of Pennsylvania, General Pediatrician at PennCare for Kids, Phoenixville, PA. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.
