Microstructural changes of brain in patients with aromatic L-amino acid decarboxylase deficiency.

Aromatic L-amino acid decarboxylase (AADC) deficiency is an uncommon inherited neurometabolic disease. The clinical presentations and MR findings in children with AADC deficiency were investigated. Total 12 children (6 boys, 6 girls), aged from 9 to 50 months (mean, 23 ±13 months), with AADC deficiency, were enrolled for analysis. Of 12 patients enrolled, clinical presentations included global developmental delay with generalized hypotonia in 12 (100%), dystonia in 12 (100%), oculogyric crisis in 12 (100%), and excessive sweating in 8 (67%). Sleep problem was also found in 4 (33%). Of 15 MR examinations, the major changes included 6 (40%) with diffusely prominent bilateral frontal sulci, 10 (67%) with prominent frontal horns, and 12 (80%) with hypomyelination. In AADC patients, the frontal horn was significantly widened (P < 0.01), and the volume of caudate nucleus was also significantly smaller than that of controls (P = 0.02). The ratios of thickness of the splenium to that of the genu of corpus callosum were also significantly increased (P < 0.01). There was also significant decrease of fiber density indices in major white matter fiber tracts. Using Tract-Based Spatial Statistics approach, we also revealed significant change in major fiber tracts related to language function and motor function. In conclusion, the present study indicated that AADC deficiency may have significant impact on brain development, especially the frontal lobe and fiber tracts related to language function and motor function. Long-term follow-up of brain MRI in patients with AADC deficiency may clarify the possible effect of AADC deficiency on brain development. Hum Brain Mapp 38:1532-1540, 2017.