Electron microscopy of chorionic villus samples for prenatal diagnosis of lysosomal storage disorders

Some lysosomal storage disorders cause progressive prenatal accumulation of undegradable metabolites that manifest as membrane-bound vacuoles in endothelial cells, fibroblasts, and trophoblast, identifiable by electron microscopic examination of chorionic villus samples (CVS). There were 111 CVS, which had ultrastructural examination for suspected storage disorders at Great Ormond Street Hospital (1988-2005). There were 31 positive diagnoses, including glycogen storage disease type II, gangliosidosis type 1, mucopolysaccharidosis type 1, MPS not specified, Niemann-Pick type A, sialidosis/mucolipidosis type 1, neuronal ceroid lipofuscinoses (including variant forms), Wolman disease, sialic acid storage disease, and storage disease not specified. In most of these cases the indication was a previously affected individual. Seventy-seven cases showed no evidence of storage disease; 3 samples were inadequate for ultrastructural diagnosis. In selected cases, one-third of CVS may demonstrate distinctive ultrastructural features allowing prenatal diagnosis of a range of storage diseases.