Clinical variability within Brachmann-de Lange syndrome: a proposed classification system.

Seven patients, including two sibs, with the Brachmann-de Lange syndrome (BDLS) are presented as representative of the different types of BDLS in a proposed classification system. Type I ("classic") patients have the characteristic facial and skeletal changes of BDLS using the criteria in the diagnostic index of Preus and Rex. Type I is distinguished from the other subtypes by prenatal growth deficiency (< 2.5 S.D. below mean for gestation) becoming more severe postnatally (< 3.5 S.D. below the mean), moderate to profound psychomotor retardation, and major malformations which result in severe disability or death. Type II ("mild") BDLS patients have similar facial and minor skeletal abnormalities to those seen in type I; however, these changes may develop with time or may be partially expressed. Patients with type II BDLS are distinguished from those with other types by mild to borderline psychomotor retardation, less severe pre- and postnatal growth deficiency, and the absence of (or loss severe) major malformations. Behavioral problems can be a significant clinical problem in type II BDLS. Type III ("phenocopies") BDLS includes patients who have phenotypic manifestations of BDLS which are causally related to chromosomal aneuploidies or teratogenic exposures.