In humans, a single transverse palmar crease is a single crease that extends across the palm of the hand

Hand

A hand is a prehensile, multi-fingered extremity located at the end of an arm or forelimb of primates such as humans, chimpanzees, monkeys, and lemurs...

, formed by the fusion of the two palmar creases (the heart line and the head line) that people typically have. Because it resembles the usual condition of non-human simian

Simian

The simians are the "higher primates" familiar to most people: the Old World monkeys and apes, including humans, , and the New World monkeys or platyrrhines. Simians tend to be larger than the "lower primates" or prosimians.- Classification and evolution :The simians are split into three groups...

s, it is also known as a simian crease or simian line, although these terms have widely fallen out of favor due to their pejorative connotation.

Medical significance

The presence of a single transverse palmar crease can be, but is not always, a symptom associated with abnormal medical conditions, such as fetal alcohol syndrome

Fetal alcohol syndrome

Fetal alcohol syndrome is a pattern of mental and physical defects that can develop in a fetus in association with high levels of alcohol consumption during pregnancy. Current research also implicates other lifestyle choices made by the prospective mother...

, or with genetic chromosomal abnormalities, including Down syndrome

Down syndrome

Down syndrome, or Down's syndrome, trisomy 21, is a chromosomal condition caused by the presence of all or part of an extra 21st chromosome. It is named after John Langdon Down, the British physician who described the syndrome in 1866. The condition was clinically described earlier in the 19th...

 (chromosome 21), cri du chat syndrome (chromosome 5),
Klinefelter syndrome, Noonan syndrome

Noonan syndrome

Noonan Syndrome is a relatively common autosomal dominant congenital disorder considered to be a type of dwarfism, that affects both males and females equally. It used to be referred to as the male version of Turner's syndrome ; however, the genetic causes of Noonan syndrome and Turner syndrome...

 (chromosome 12), Patau syndrome

Patau syndrome

Patau syndrome, also known as trisomy 13 and trisomy D, is a chromosomal abnormality, a syndrome in which a patient has an additional chromosome 13 due to a nondisjunction of chromosomes during meiosis. Some are caused by Robertsonian translocations...

 (chromosome 13), Edward's syndrome (chromosome 18), and Aarskog-Scott syndrome

Aarskog-Scott syndrome

Aarskog–Scott syndrome is an inherited disease characterized by short stature, facial abnormalities, skeletal and genital anomalies.The Aarskog–Scott syndrome is also known as the Aarskog syndrome, faciodigitogenital syndrome, shawl scrotum syndrome and faciogenital dysplasia.-Signs and...

 (X-linked recessive). Bilateral or unilateral single palmar creases are also associated with aberrations on chromosome 9. It is also sometimes found on the hand of the affected side of patients with Poland Syndrome

Poland syndrome

Poland syndrome is a rare birth defect characterized by underdevelopment or absence of the chest muscle on one side of the body and webbing of the fingers of the hand on the same side mostly common on the right...

 and craniosynostosis

Craniosynostosis

Craniosynostosis is a condition in which one or more of the fibrous sutures in an infant skull prematurely fuses by ossification, thereby changing the growth pattern of the skull...

.

Males are twice as likely as females to have this characteristic, and it tends to run in families. In its non-symptomatic form, it is more common among Asians and Native Americans than among other populations, and in some families there is a tendency to inherit the condition unilaterally, that is, on one hand only.

External links

• An example of a single transverse palmar crease