A behavioral phenotype in the de Lange syndrome.

The behavior of nine patients with the de Lange syndrome was studied using videotape, a recording protocol of eight standardized stimulus conditions, and a visual, digital time reference which permitted precise coding and quantitative analysis. These patients avoid or reject social interactions and physical contact, and they do not distinguish in this between a stranger and the mother or her substitute. Social interactions with the adult stranger were scored in patients 1-7 as negative for 28-56 sec/min, whereas they were positive for 1-6 sec/min. Statistical significance was at the level of P less than 0.01. In the case of the mother negative responses ranged from 21-45 sec/min and positive from 3-27 sec/min. The patients exhibit infrequent facial expressions of emotion, and frequently display stereotypic movements. On the other hand, vestibular stimulation or vigorous movement appeared to be an effective means of eliciting pleasurable responses. When held in arms in the vertical position only one of nine children smiled at all and the frequency for that child was 0.8/min. When the child was bounced vigorously in the same position, all smiled but who was too large to be bounced. In the eight the frequency of smiling ranged from 0.8-3.6/min. The data obtained indicate that a specific behavioral phenotype is associated with this syndrome.