Single Transverse Palmar Crease
A 6-month-old boy presented to a pediatric clinic for a well-child examination. The mother was concerned about the boy’s weight gain pattern—he had fallen from the 50th percentile on the growth chart at his 2-month checkup to the 25th percentile at the current visit. The infant had been breastfed exclusively, and the mother asked whether she needed to switch from breastfeeding to formula feeding in order for him to gain more weight.
During the physical examination, both of the boy’s palms were noted to have a single straight line from one side to the other, consistent with bilateral single transverse palmar crease. The mother explained that because of this feature, the boy had undergone extensive workup including genetic testing, and his developmental milestones and head circumference had been monitored closely. This made the parents anxious, and the mother suggested that the boy’s slowing growth pattern could be attributed to decreased breast milk production resulting from this anxiety. Nevertheless, the child had been doing well and was active, and his developmental milestones were otherwise appropriate.
Single transverse palmar crease (STPC), formerly known as a simian crease, is characterized by the presence of a single crease that runs the breadth of the hand and is formed from the fusion of the two palmar creases. The STPC develops in utero and is fully formed by the 12th week of gestation.1 It is present in 1 of 30 newborns, with boys being twice as likely to exhibit the phenotype as girls.1 STPCs are commonly inherited and are more prevalent in infants with lower birth weights.2
STPC is found in approximately 60% of the population with Down syndrome.3 STPC often also is associated with Aarskog syndrome, Cohen syndrome, fetal alcohol syndrome, trisomy 13 syndrome, congenital rubella syndrome, Turner syndrome, Klinefelter syndrome, pseudohypoparathyroidism, and cri du chat syndrome.1
In many cases, STPC is idiopathic, and most individuals with it have no related underlying conditions. Because STPC is much more common than Down syndrome, STPC does not always indicate Down syndrome. STPC affects approximately 1 in 30 individuals, while Down syndrome affects approximately 1 in 691 individuals, 61.1% of whom have STPC.
A child’s having been born with STPC should not be a cause for concern for parents or health care providers, unless the child manifests other symptoms of an associated condition or is at a higher risk for an associated condition. In such cases, further examination is required for diagnosis. Karyotype testing can determine whether a child has Down syndrome or other chromosomal anomalies (eg, cri du chat syndrome, Klinefelter syndrome, etc). Family history also should be considered. Maternal alcohol consumption during pregnancy and the age of the child’s parents also can be contributing factors.
References
1. Kaneshiro NK. Simian crease. MedlinePlus. http://www.nlm.nih.gov/medlineplus/ency/article/003290.htm. Updated May 20, 2013. Accessed September 11, 2015.
2. Dar H, Carney FE Jr, Winter ST. Dermatoglyphics and the simian crease in infants of low birth weight: a pilot study. Acta Paediatr Scand. 1971;60(4):479-481.
3. Sureshbabu R, Kumari R, Ranugha S, Sathyamoorthy R, Udayashankar C, Oudeacoumar P. Phenotypic and dermatological manifestations in Down syndrome. Dermatol Online J. 2011;17(2):3.