Single palmar crease

Single transverse palmar crease
Single transverse palmar crease on an infant's hand
Classification and external resources
ICD-9-CM	757.2 (CDC/BPA 757.200)
MedlinePlus	003290
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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 (known in palmistry as the "heart line" and the "head line") and is found in half of people with Down Syndrome. It is also found in 1.5% of the general population in at least one hand.

Because it resembles the usual condition of non-human simians, 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.

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 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, or with genetic chromosomal abnormalities, including Down Syndrome (chromosome 21), cri du chat syndrome (chromosome 5), Klinefelter syndrome, Wolf-Hirschhorn Syndrome, Noonan syndrome (chromosome 12), Patau syndrome (chromosome 13), Edward's syndrome (chromosome 18), and Aarskog-Scott syndrome (X-linked recessive), or autosomal recessive disorder, such as Leaukocyte adhesion deficiency-2 (LAD2). 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 hand of the affected side of patients with Poland Syndrome, and craniosynostosis.

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