Aspects of skeletal development in fragile X syndrome fetuses

The purpose of the present investigation was to describe the skeletal devel opment in prenatal fragile X syndrome. We studied fetuses (4 males, 2 femal es), with gestational ages (GA) 12-14 weeks, from 5 unrelated, different, k nown carrier mothers. Because of trauma to the fetus during abortion, diffe rent parts of the 6 fetuses were available for investigation. The vertebral column and the facial skeleton of all the fetuses were examined, the feet and hands of 5 fetuses, and the cranial base of 3 fetuses. The tissue remna nts were examined radiographically and histochemically, and the results com pared with previously published normal findings. Radiographic findings incl uded normal ossification sequence, except for 1 fetus where there was an ab normal, sequence in the first finger; normal morphology of ossification cen tres; and nasal bones were absent in the 5 fetuses and present in 1 (14 wee ks of gestation). The histological study suggests presence of an acid mucop olysaccharide malfunction in the supporting tissue, because the normal cart ilage resorption and orthochromatic cartilage reactions do not appear durin g the initial enchondral ossification. In addition, the apoptosis of ectode rmally derived cells (notochord and palatal epithelial layers) appears dela yed or abnormal. The sella turcica was malformed in the 2 fetuses investiga ted for sella turcica morphology, (C) 2000 Wiley-Liss, Inc.