Analysis of intracranial volume in Apert syndrome genotypes

Objective: Apert syndrome is caused by a mutation of the fibroblastic growth factor type 2 gene and in nearly all of the cases where the mutation has been identified it occurs in one of two adjacent sites of the gene, either position 252 or position 253. There is currently uncertainty whether a worse neurosurgical outcome occurs in association with a particular genotype. We investigated whether there were clinically subtle (but relevant) morphological differences in the craniofacial skeleton, which would result in differences in the intracranial volume, which might account for apparent differences in surgical outcome. Method: Three-dimensional CT scans of preoperative Apert syndrome whose genotype had been identified had the intracranial volume measured using the Cavalieri estimator with correction for partial voluming effects. The values were compared to age and sex normals and then the two genotypes compared. Results: Intracranial volumes were measured for 22 cases, 16 with the 252 mutation and 6 with the 253 mutation. Conclusions: All cases except two had greater than their sex- and age-adjusted mean normal intracranial volumes. For the 252 and 253 genotypes there were no discernible differences in intracranial volumes between the two genotypes.