METACARPOPHALANGEAL ANALYSIS IN CROUZON-SYNDROME - ADDITIONAL EVIDENCE FOR PHENOTYPIC CONVERGENCE WITH THE ACROCEPHALOSYNDACTYLY SYNDROMES

Crouzon syndrome (CS) is characterized by premature craniosynostosis, orbital proptosis, and midfacial hypoplasia and is related to the acro cephalosyndactylies (ACS) with limb abnormalities. In CS the hands are considered to be normal, but a previous report indicated that there i s consistent alteration in the proportions of the bones of the hands, as shown by metacarpophalangeal analysis (MCPP), in at least some case s of CS, The purpose of this study was to extend these findings by exa mining affected individuals and their supposedly unaffected first degr ee relatives. If CS does have an effect on hands, then this should onl y be evident in the affected individuals and, presuming complete penet rance, not present in their unaffected relatives, PA hand films were t aken on 12 CS subjects and 16 of their normal relatives. The lengths o f the metacarpals and phalanges were measured and the measurements sta ndardized for age and sex by conversion to z-scores using published no rmal standards. Mean pattern profiles for the 2 groups were plotted, I n CS the phalanges, especially the first and second proximal phalanges and the first distal phalanx, were shorter than average, and shorter than those of unaffected relatives, The metacarpals were not significa ntly smaller than the reference means in CS, The 19 hand measurements were entered into a stepwise forward discriminant function analysis (D FA) to develop a model that would discriminate between CS subjects and their normal first degree relatives, The function generated used the measurements of 8 hand bones to classify correctly CS subjects and the ir normal relatives 100% of the time, This study confirmed that there is a radiographically detectable abnormality of the hands in CS and th at, at least in this sample, relatives did not display such abnormalit ies. Therefore, it seems that CS shares postcranial effects with true ACS and that these effects are, like the other aspects of CS, fully pe netrant. (C) 1997 Wiley-Liss, Inc.