âSimian creaseâ is an outdated term that is no longer considered politically correct; âsimianâ refers to an ape or monkey, or something having the characteristics of these animals. Single transverse palmar crease (STPC) is a more accurate name for this condition.
The skin of a normal palm has three large creases. The distal transverse palmar crease runs near the top of palm and begins close to the little finger. The thenar transverse crease is the lowest on the palm and appears to run almost vertically. The proximal transverse palmar crease lies between the other two creases.
In cases of SPTC, the distal and proximal creases are not present. Instead, they combine to form one transverse palmar crease. The thenar transverse crease remains the same.
STPC occurs in about one in 30 individuals, and males are twice as likely to have this condition as females. Sometimes, STPC is a symptom of disorders such as Down syndrome, or may be an early indicator of developmental problems. However, this is usually not the case.
STPC develops while a baby is growing in the motherâs womb, during the first trimester, when palm creases develop.
SPTC may be idiopathic (without an identifiable cause). The condition is relatively common, and most individuals with SPTC are perfectly healthy and have no underlying conditions. However, for others, having a STPC may be a warning sign of an undiagnosed condition.
STPC can be a valuable symptom in the early diagnosis of a number of disorders. The most well known disorder of which STPC is a symptom is Down syndrome. Down syndrome is a developmental disorder that results most often from an extra genetic copy of chromosome 21.
Disorders of which STPC is a diagnostic sign include:
Unless it is associated with another condition, such as Down syndrome, STPC does not indicate any medical problem. 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 (Suresh, 2011).