Cortical Defects, Wormian Bones, And Dentinogenesis Imperfecta

Clinical Features

Suarez and Stickler (1974) reported an 8-year-old girl, the daughter of nonconsanguineous parents, whom they described as having short, thick arms and fingers, a broad saddle-like nose, and a normal height for age. She had a fracture of the forearm at 2 weeks of age and a pathologic fracture of the right tibia at the age of 6 years. Radiographs of the tibia and the long bones of the upper arms showed scattered radiolucent cortical defects with associated areas of cortical thickening. There were multiple wormian bones in the skull. The teeth were not described. Cognitive development was normal.

Moog et al. (1999) reported 2 sibs with striking similarity in clinical and radiographic features to the child described by Suarez and Stickler (1974). They were born to Dutch nonconsanguineous parents and had normal cognitive development. The older sib, a 6-year-old boy, had fractures affecting the tibiae following minimal trauma at ages 4, 5, and 6 years. Radiographs showed almost identical cortical lesions to those of the child reported by Suarez and Stickler (1974). These were not present in the younger sib at the age of 22 months. Both children had multiple wormian bones but no osteopenia. The younger child had a widely open anterior fontanel at 22 months. Heights were at or below 3rd centile for age. They had hypertelorism and orbital fullness. The teeth were small, translucent, and susceptible to caries. The mother, who had no radiographic abnormalities of the skull, legs, or hands, also had translucent teeth. Electrophoresis of collagen from cultured fibroblasts and analysis of the 3-prime untranslated regions of COL1A1 (120150) and COL1A2 (120160) in genomic DNA and cDNA gave normal results. Karyotype, bone biochemistry, and metabolic screening were normal. Moog et al. (1999) pointed out the similarities between their cases and that of Suarez and Stickler (1974) and differentiated them from osteogenesis imperfecta (see 166200), Hajdu-Cheney syndrome (102500), and serpentine fibula syndrome on the basis of collagen studies, lack of osteopenia, the presence of cortical defects, which they believe to be pathognomic, lack of osteolysis, and facial phenotype.

Inheritance

Moog et al. (1999) proposed either autosomal recessive inheritance, with dentinogenesis imperfecta in the mother and children representing a separate entity (dentinogenesis imperfecta type II; 125490), or, alternatively, autosomal dominant inheritance with dentinogenesis imperfecta forming part of this condition, with the lack of other features in the mother due to variable expression.