Overgrowth of oral mucosa and facial skin, a novel feature of aspartylglucosaminuria

Aspartylglucosaminuria (AGU) is a lysosomal storage disorder caused by defi ciency of aspartylglucosaminidase (AGA). The main symptom is progressive me ntal retardation. A spectrum of different mutations has been reported in th is disease, one missense mutation (Cys163Ser) being responsible for the maj ority of Finnish cases. We were able to examine 66 Finnish AGU patients for changes in the oral mucosa and 44 of these for changes in facial skin. Bio psy specimens of 16 oral lesions, 12 of them associated with the teeth, plu s two facial lesions were studied histologically. Immunohistochemical stain ing for AGA was performed on 15 oral specimens. Skin was seborrhoeic in adolescent and adult patients, with erythema of the facial skin already common in childhood. Of 44 patients, nine (20%) had fa cial angiofibromas, tumours primarily occurring in association with tuberou s sclerosis. Oedemic buccal mucosa (leucoedema) and gingival overgrowths we re more frequent in AGU patients than in controls (p<0.001). Of 16 oral mucosal lesions studied histologically, 15 represented fibroepit helial or epithelial hyperplasias and were reactive in nature. Cytoplasmic vacuolisation was evident in four. Immunohistochemically, expression of AGA in AGU patients' mucosal lesions did not differ from that seen in correspo nding lesions of normal subjects. Thus, the high frequency of mucosal overg rowth in AGU patients does not appear to be directly associated with lysoso mal storage or with alterations in the level of AGA expression.