Monoamine oxidase and catechol-o-methyltransferase activity in cultured fibroblasts from patients with maple syrup urine disease, Lesch-Nyhan syndrome and healthy controls.

Monoamine oxidase (MAO) and catechol-o-methyl transferase (COMT) activities have been measured in fibroblasts from nine healthy controls, three patients with maple syrup urine disease (MSUD) and six patients with Lesch-Nyhan syndrome. Both A and B types of MAO activity are found in these cell lines. In comparison to controls, the MAO activity is significantly reduced in cells from patients with Lesch-Nyhan syndrome. A different situation has been observed in the cell lines from MSUD patients: one showed a high MAO activity, another a significantly reduced activity, and the third was in the range of the normal controls. COMT activity is also present in these cells, but with a wide variation. No specific differences have been noted among the controls and the mutant cells.