Complementation studies in human and caprine β‐mannosidosis

Abstract

Cell fusions were performed to investigate the possible involvement of different gene mutations in five patients with isolated beta-mannosidosis and a patient with a combined deficiency of beta-mannosidase and heparin sulphate sulphamidase. In none of the combinations of cell lines was beta-mannosidase activity restored in the fused cell culture. Similarly, no complementation of sulphamidase activity was observed after fusion of cells with the combined deficiency and cells with isolated sulphamidase deficiency (mucopolysaccharidosis type IIIA). The absence of complementation suggests that the combined deficiency is not caused by a defect in one common factor affecting the two enzymes: The results rather indicate a rare coincidence of two independent mutations which are allelic with the mutation in the respective conditions with isolated enzyme deficiencies.

Human β‐mannosidosis: a 3‐year‐old boy with speech impairment and emotional instability

“…Complementation studies in fused cell cultures made by Hu et al (1991) (fibroblast strains from five patients with P-mannosidase deficiency and the patient with combined P-mannosidosis and sulphamidase deficiency) do not show restoration of any enzyme activity. This result rules out the presence of possible inhibitors and suggests that human P-mannosidosis is caused by allelic mutations, probably in the structural P-mannosidase gene.…”

β-mannosidase deficiency in two mentally retarded girls with intractable seizures

“…Studies have suggested that human and caprine β-mannosidosis are both most likely caused by allelic mutations in the structural β-mannosidase genes. 14 Recent studies on mutation analysis have identified the gene localized to chromosome 4q22–25, 15 and the gene consisting of 17 exons. 16 Prenatal diagnosis is possible in this condition since β-mannosidase activity is highly expressed in chorionic villi and amniotic cells.…”