Progressive mental regression in siblings with Morquio disease type B (mucopolysaccharidosis IV B).

Abstract

A brother and sister with clinical and radiological features of Morquio disease, but with atypical mental regression, are described. Leucocyte and fibroblast beta-galactosidase activity was deficient in the siblings, while N-acetylgalactosamine 6-sulphate sulphatase and neuraminidase were normal. Study of the residual fibroblast beta-galactosidase activity towards 4-methylumbelliferyl and p-nitrophenyl beta-D-galactosides indicated that the mutation resembles that in typical Morquio B disease (increased Km and similar pH maximum) rather than that in GM1-gangliosidosis. The patients have therefore been classified as having Morquio B disease with atypical mental regression rather than GM1-gangliosidosis variants with particularly severe bony abnormalities. The mutation was, however, distinct from that in Morquio B disease since residual activity towards the alternative artificial substrate 4-methylumbelliferyl-beta-D-fucoside was increased. The patients represent further examples of the heterogeneity that can result from mutation at the beta-galactosidase locus.

• Authors: R Giugliani, M Jackson, S J Skinner, C M Vimal, A H Fensom, N Fahmy, A Sjövall, P F Benson
• Journal: Clinical genetics (Clin Genet) Vol. 32 Issue 5 Pg. 313-25 (Nov 1987) ISSN: 0009-9163 [Print] Denmark
• PMID: 3121219 (Publication Type: Case Reports, Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• beta-Galactosidase

Topics

• Bone Diseases, Developmental (diagnostic imaging, enzymology, genetics)
• Child
• Chronic Disease
• Diagnosis, Differential
• Female
• Humans
• Intellectual Disability (enzymology, genetics)
• Male
• Mucopolysaccharidosis IV (enzymology, genetics)
• Radiography
• beta-Galactosidase (metabolism)