RADIOLOGICAL AND HISTOLOGICAL VARIANTS OF THANATOPHORIC DYSPLASIA AREASSOCIATED WITH COMMON MUTATIONS IN FGFR-3

We describe two fetuses of the 21st week of gestation that share some macroscopic, radiologic, and histologic findings of thanatophoric dysp lasia (TD), but also show distinct differences from the usual subtypes of TD. These differences mainly comprise the lack of facial abnormali ty, only mild reduction of chondrocyte proliferation and hypertrophy, and the lack of fibrous tissue interposition between cartilage and per iosteal bone. Thus, these two cases may represent a distinct variant o f thanatophoric dysplasia. The molecular analysis of the FGF-R-3 gene demonstrated in both cases mutations which were not significantly diff erent from those of other cases of TD. Thus, the phenotypic modulation within the subtypes of TD may be influenced by additional and yet unk nown factors. (C) 1996 Wiley-Liss, Inc.