Atypical Gilles de la Tourette Syndrome with beta-mannosidase deficiency.

Background: beta-Mannosidosis is a rare inborn error of metabolism with various phenotypes, including mental retardation, behavioral problems, hearing loss, and recurrent airway infections in childhood. To our knowledge, there is no published description of Gilles de la Tourette syndrome in association with this enzymatic deficiency.

Objective: To describe a unique case of Gilles de la Tourette syndrome associated with beta-mannosidosis.

Setting: University hospital. Patient An 18-year-old man exhibited motor and vocal tics since childhood, attention-deficit/hyperactivity disorder, impulsivity, and aggressiveness compatible with Gilles de la Tourette syndrome. A screen for inborn errors of metabolism was made because of the atypical association with slight mental retardation and bilateral perceptive hypoacousia.

Results: Urinary analysis showed disacchariduria, and leukocyte analysis revealed a profound deficit in beta-mannosidase activity. Two novel mutations in the beta-mannosidase gene were found: a new splice mutation in one allele, and a unique 10-base-pair insertion in the other.

Conclusions: This case illustrates the phenotypic variability of inborn errors of metabolism in adults and demonstrates the need to screen inborn errors of metabolism in atypical Gilles de la Tourette syndrome.