Fluctuating asymmetry and vertebral malformation. A study of palmar dermatoglyphics in congenital spinal deformities.

Abstract

Prints of palmar dermatoglyphics (epidermal ridges) of individuals with congenital vertebral anomaly were compared, using symmetry criteria, with those of healthy control individuals. Asymmetries have been reported in adolescent idiopathic scoliosis and, from other centers, in other congenital anomalies, such as cleft lip and palate. Application of these methods to congenital vertebral anomaly seemed promising. To challenge the hypothesis that, in congenital vertebral anomaly, epigenesis was disrupted by nonspecific physiologic stress during the embryonic period, resulting in anatomic malformations. Dermatoglyphics (palmar epidermal ridges) are formed at the end of the embryonic period under genetic control and do not change thereafter. They thus give an indication of the stability or otherwise of development at that early stage. This led to the hypothesis that congenital vertebral anomaly results from destabilization of genetic developmental control in the embryonic period. The dermatoglyphics of 126 healthy control individuals and 99 people with congenital vertebral anomaly were compared quantitatively, using right-left differences of atd angles and ab, bc, and cd ridge counts. Fluctuating asymmetry (a significantly increased variance about the mean) was observed in individuals with congenital vertebral anomaly. This is a measure of instability of genetic development processes and the increased probability that these processes will be destabilized by environmental stress during ontogeny. They also showed an increased incidence of ridge dissociation, suggestive of a generalized insult during the embryonic period. These findings suggest that congenital vertebral anomalies arise from a nonspecific insult during the embryonic period that destabilizes the developmental control systems and may result in congenital malformations of any organ undergoing concurrent epigenesis.