The patient described is the first case of TSD in the Cypriot population. The clinical features of the patient
are similar to those reported for other juvenile TSD cases (Maegawa et al., 2006). The diagnosis was
established with the measurement of Hex A activity. A low percentage of Hex A activity was found in plasma
(5%, normal 52–78%), and leucocytes (12%, normal 49–70%). The deficiency of hexosaminidase A was
confirmed in cultured fibroblasts using the MUGS substrate (total hexosaminidase and β-galactosidase were