In humans, a single transverse palmar crease is a single crease that extends across the palm of the
hand
A hand is a prehensile, multi-fingered appendage located at the end of the forearm or forelimb of primates such as humans, chimpanzees, monkeys, and lemurs. A few other vertebrates such as the koala (which has two opposable thumbs on each "h ...
, formed by the fusion of the two
palmar crease
A palmar crease is a type of crease on the palm. A single transverse palmar crease also called simian crease is sometimes associated with Down syndrome. Other types of creases include the Sydney crease and the Suwon, or double transverse palmar c ...
s (known in
palmistry
Palmistry is the Pseudoscience, pseudoscientific practice of fortune-telling through the study of the Hand#Areas, palm. Also known as palm reading, chiromancy, chirology or cheirology, the practice is found all over the world, with numerous cul ...
as the "heart line" and the "head line"). 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 perfectly healthy persons. It is found in 1.5% of the world population in at least one hand.
Former name
Because it resembles the usual condition of non-human
simian
The simians, anthropoids, or higher primates are an infraorder (Simiiformes ) of primates containing all animals traditionally called monkeys and apes. More precisely, they consist of the parvorders New World monkeys (Platyrrhini) and Catarrhi ...
s, 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
The presence of a single transverse palmar crease has no medical significance. It is found in 1.5% of all people, and though it is found at a higher frequency in people with abnormal medical conditions, in every one of these conditions many people do not have a single transverse palmer crease, thus it has low predictive value.
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.
While it is often found in people with Down Syndrome, many who have this syndrome do not have this crease, and thus is not a diagnostic indicator of the Down Syndrome.
The presence of a single transverse palmar has been associated with a number of abnormal medical conditions — that is, it is found at a higher than 1.5% frequency, but in all of these conditions many do not have this crease. Examples of conditions with such an association are
fetal alcohol syndrome, and with the genetic chromosomal abnormalities
Down syndrome
Down syndrome or Down's syndrome, also known as trisomy 21, is a genetic disorder caused by the presence of all or part of a third copy of chromosome 21. It is usually associated with physical growth delays, mild to moderate intellectual dis ...
(
chromosome 21
Chromosome 21 is one of the 23 pairs of chromosomes in humans. Chromosome 21 is both the smallest human autosome and chromosome, with 48 million base pairs (the building material of DNA) representing about 1.5 percent of the total DNA in cells. ...
),
cri du chat syndrome
Cri du chat syndrome is a rare genetic disorder due to a partial chromosome deletion on chromosome 5. Its name is a French term ("cat-cry" or " call of the cat") referring to the characteristic cat-like cry of affected children. It was first de ...
(
chromosome 5
Chromosome 5 is one of the 23 pairs of chromosomes in humans. People normally have two copies of this chromosome. Chromosome 5 spans about 181 million base pairs (the building blocks of DNA) and represents almost 6% of the total DNA in cells. Ch ...
),
Klinefelter syndrome
Klinefelter syndrome (KS), also known as 47,XXY, is an aneuploid genetic condition where a male has an additional copy of the X chromosome. The primary features are infertility and small, poorly functioning testicles. Usually, symptoms are su ...
,
Wolf-Hirschhorn Syndrome,
Noonan syndrome
Noonan syndrome (NS) is a genetic disorder that may present with mildly unusual facial features, short height, congenital heart disease, bleeding problems, and skeletal malformations. Facial features include widely spaced eyes, light-colored ...
(
chromosome 12
Chromosome 12 is one of the 23 pairs of chromosomes in humans. People normally have two copies of this chromosome. Chromosome 12 spans about 133 million base pairs (the building material of DNA) and represents between 4 and 4.5 percent of the to ...
),
Patau syndrome
Patau syndrome is a syndrome caused by a chromosome, chromosomal abnormality, in which some or all of the Cell (biology), cells of the body contain Trisomy, extra genetic material from chromosome 13 (human), chromosome 13. The extra genetic mater ...
(
chromosome 13
Chromosome 13 is one of the 23 pairs of chromosomes in humans. People normally have two copies of this chromosome. Chromosome 13 spans about 114 million base pairs (the building material of DNA) and represents between 3.5 and 4% of the total DNA ...
),
IDIC 15/Dup15q (
chromosome 15
Chromosome 15 is one of the 23 pairs of chromosomes in humans. People normally have two copies of this chromosome. Chromosome 15 spans about 102 million base pairs (the building material of DNA) and represents between 3% and 3.5% of the total DNA ...
),
Edward's syndrome (
chromosome 18
Chromosome 18 is one of the 23 pairs of chromosomes in humans. People normally have two copies of this chromosome. Chromosome 18 spans about 80 million base pairs (the building material of DNA) and represents about 2.5 percent of the total DNA in ...
), and
Aarskog-Scott syndrome (X-linked recessive), or autosomal recessive disorder, such as
Leukocyte adhesion deficiency-2 (LAD2). A unilateral single palmar crease was also reported in a case of
chromosome 9
Chromosome 9 is one of the 23 pairs of chromosomes in humans. Humans normally have two copies of this chromosome, as they normally do with all chromosomes. Chromosome 9 spans about 138 million base pairs of nucleic acids (the building blocks of D ...
mutation causing
Nevoid basal cell carcinoma syndrome
Nevoid basal-cell carcinoma syndrome (NBCCS) is an inherited medical condition involving defects within multiple body systems such as the skin, nervous system, eyes, endocrine system, and bones. People with this syndrome are particularly prone to ...
and
Robinow syndrome
Robinow syndrome is an extremely rare genetic disorder characterized by short-limbed dwarfism, abnormalities in the head, face, and external genitalia, as well as vertebral segmentation. The disorder was first described in 1969 by human geneticist ...
. It is also sometimes found on the hand of the affected side of patients with
Poland syndrome
Poland syndrome is a birth defect characterized by an underdeveloped chest muscle and short webbed fingers on one side of the body. There may also be short ribs, less fat, and breast and nipple abnormalities on the same side of the body. Typical ...
, and
craniosynostosis
Craniosynostosis is a condition in which one or more of the fibrous sutures in a young infant's skull prematurely fuses by turning into bone (ossification), thereby changing the growth pattern of the skull. Because the skull cannot expand perpe ...
.
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.
Image:Single transverse palmar crease adult.jpg, Single transverse palmar crease in an adult
Image:Normal creases adult.jpg, More common palmar creases in adults
See also
*
Dermatoglyphics
Dermatoglyphics (from Ancient Greek ''derma'', "skin", and ''glyph'', "carving") is the scientific study of fingerprints, lines, mounts and shapes of hands, as distinct from the superficially similar pseudoscience of palmistry.
Dermatoglyphics a ...
References
External links
{{Use dmy dates, date=April 2017
Hand
Down syndrome