Dermatoglyphs of digito-palmar complex in autistic disorder: family analysis

To examine the role of the genetic component in the quantitative dermatoglyphic traits of autistic patients and their families, and the transmission of the autism.

Finger and palm prints were taken from 120 autistic patients (92 males and 28 females), their parents (92 mothers and 70 fathers), 32 healthy brothers and 28 sisters, as well as 400 healthy controls (200 males and 200 females). An analysis of quantitative traits of dermatoglyphs on the fingers (FRC - finger ridge count) and palms (a-b, b-c, and c-d ridge count, and atd angle) was performed. Descriptive statistics, multivariate analysis of variance (MANOVA) with Tukey HSD post hoc test, and discriminant analysis were used to determine the differences among the groups. In addition, correlations among family members were analyzed.

Multivariate analysis showed significant differences among examined groups of autistic patients and their family members and healthy volunteers regarding both group membership and sex. Autistic male patients differed significantly from the healthy controls in the ridge count (RC) on the fourth and fifth finger, and in a-b RC and atd angle of both hands. Healthy fathers of autistic patients differed in atd angle, and brothers of autistic patients differed in all palmar variables from the healthy control group. Mothers of autistic patients differed significantly from the healthy female controls in the RC of the first, fourth, and fifth finger, in a-b and c-d RC on the palms, and atd angle of both hands. The first two discriminant functions explained 85.4% of variance and separated groups clearly in two ways: the first function separated healthy controls from family members of autistic patients, and the second one males from females. Interfamilial analysis showed significant interclass correlations between autistic sons and their mothers or fathers in practically all variables. However, the correlation between parents and their autistic daughters was lower. Both mothers and fathers of autistic patients correlated with their healthy children only in palmar variables.

We found significant differences in ridge counts on the fingers and palms between the affected patients and their healthy controls, but these differences also existed between family members of autistic patients and healthy controls. Particularly pronounced were the differences between healthy female controls and female family members, including not only autistic female patients, but also their healthy mothers and sisters. Since the mothers and their autistic sons showed higher statistically significant correlation in most of the examined variables, unlike the mothers and their autistic or healthy daughters, it is possible that there is a connection between a recessive X-chromosome linkage, as a genetic component in the etiology of autistic disorders, and the influence of the inactivation of the affected X-chromosome in the females.