DETECTION OF ARYLSULFATASE A IN LEUKOCYTES AND URINES OF LATE INFANTILE METACHROMATIC LEUKODYSTROPHY REPORT OF 3 CASES

Two male siblings and one female from two unrelated families were affected by late infantile metachromatic leukodystrophy (MLD) with similar clinical manifestations. Ary:sulfatase A (ASA) activi- ties in dialyzed urines and in leukocytes were deter mined. Urinary ASA activities of patients at a pH opti- mum of 5.0 were below the lower limit of the nor mals, but increased when assays were carried out at pH 5.6, while it fell in normals or non-MLD pa tients with a rise in pH. Leukocyte ASA activities in a proband were also below the lower limit of normal controls. Urinary ASA activities of 3 0f 4 parents were normal. Leukocyte ASA activities in all of the parents were intermediate between those of the pro bands and those of normal controls. Urinary ASA determination might be used as a screening test for MLD patients but not reliable for heterozygote detection. The confirmation of the diagnosis should rely upon leukocyte or fibroblastic ASA determination.