Prenatal exclusion of late infantile metachromatic leucodystrophy in a late-presenting pregnancy by assay of fetal leucocytes.

Metachromatic leucodystrophy was excluded in a fetus at risk, by assay of fetal blood collected at fetoscopy. Isolated fetal leucocytes were shown to have activities of arylsulphatase A and cerebroside sulphatase in the heterozygous range. The prediction was confirmed in the newborn.