Palmar Creases: Classification, Reliability and Relationships to Fetal Alcohol Spectrum Disorders (FASD)
A normal human palm contains 3 major creases: the distal transverse crease; the proximal transverse crease; and the thenar crease. Because permanent crease patterns are thought to be laid down during the first trimester, researchers have speculated that deviations in crease patterns could be indicative of insults during fetal development. The purpose of this study was twofold: 1) to compare the efficacy and reliability of two coding methods, the first (M1) classifying both “simian” and Sydney line variants and the second (M2) counting the total number of crease points of origin on the radial border of the hand; and 2) to ascertain the relationship between palmar crease patterns and fetal alcohol spectrum disorders (FASD). Bilateral palm prints were taken using the carbon paper and tape method from 237 individuals diagnosed with FASD and 190 unexposed controls. All prints were coded for crease variants under M1 and M2. Additionally, a random sample of 98 matched (right and left) prints was selected from the controls to determine the reliabilities of M1 and M2. For this analysis, each palm was read twice, at different times, by two readers. Intra-observer Kappa coefficients were similar under both methods, ranging from 0.804-0.910. Inter-observer Kappa coefficients ranged from 0.582–0.623 under M1 and from 0.647–0.757 under M2. Using data from the entire sample of 427 prints and controlling for sex and ethnicity (white v. non-white), no relationship was found between palmar crease variants and FASD. Our results suggest that palmar creases can be classified reliably, but palmar crease patterns may not be affected by fetal alcohol exposure.