Normal α-L-fucosidase and other lysosomal enzyme activities in progressive cone dystrophy

We conducted a cross-sectional study of 24 patients with cone dystrophy to investigate a possible link between this disease and deficient activity of α-L-fucosidase. We studied patients with several forms of cone dystrophy, including six with similar clinical characteristics to two patients previously reported to be α-L-fucosidase deficient. Activities for α-L-fucosidase and several other lysosomal enzymes (β-D-glucuronidase, β-D-hexosaminidase (A + B), and α-D-mannosidase) were determined in serum and leukocytes. None of our patients with cone dystrophy were deficient in α-L-fucosidase or any other lysosomal enzyme investigated. No relationship was found between α-L-fucosidase deficiency and any type of cone dystrophy studied.