Long first metacarpal in monozygotic twins with probable Baller-Gerold syndrome

We report on a pair of monozygotic twins with probable Baller-Gerold syndro me (BGS), Twin A had severe coronal craniosynostosis, Twin B had right radi oulnar and ipsilateral first metacarpal hypoplasia, Both had bilateral fift h finger clinodactyly. Assuming that the twins were truly monozygotic, a si ngle genetic disorder (i.e., BGS) could explain the variable expression. To gether the twins have the typical anomalies of BGS. The diagnosis was suppo rted by the metacarpophalangeal profile (MPP) which confirmed hypoplasia of the first right metacarpal in Twin A and bilateral fifth finger brachymeso phalangy in both twins, Furthermore, the MPP showed an unexpected abnormal lengthening of the first metacarpal (unilateral in Twin A and bilateral in Twin B), a previously undetected radial ray defect in BGS. These findings s uggest the possibility that the MPP may assist recognition of mild cases of BGS such as those with apparently isolated craniosynostosis or isolated up per limbs defects, Am. J. Med. Genet. 80:303-308, 1998. (C) 1998 Wiley-Liss , Inc.