1/3. Heterogeneity of Morquio disease.Further clinical heterogeneity of Morquio disease, mucopolysaccharidosis iv (MPS IV), is delineated by the observation of a 30-year-old man with unusually mild clinical manifestations. He is 156 cm tall, has comparatively mild skeletal abnormalities and fine corneal deposits. Keratosulfaturia is absent. N-acetylgalactosamine-6-sulfate (GalNAc-6-S) sulfatase (E.C. 3.1.6.-) was markedly reduced in his fibroblasts. The residual enzyme activity exhibited a pH profile comparable to that of patients with the "classical" form of the disorder. From our observation and a review of the literature it is concluded that Morquio disease can be divided in several subgroups: besides the severe ("classical") type A there exist an intermediate and a mild form that are also caused by a GalNAc-6-S sulfatase deficiency. A late-onset variant of Morquio disease, which is due to a deficiency of beta-galactosidase, has been classified as type B. In addition, patients with mild manifestation of the disease and normal activities in fibroblasts of GalNAc-6-S sulfatase and beta-galactosidase have been observed (type C). The genetic nature of the broad clinical variability of Morquio disease is incompletely understood: it is partially caused by different enzyme defects. Other factors thought to influence the clinical expression include the pH profile of the residual enzyme activity and an additional neuraminidase defect.- - - - - - - - - - ranking = 1keywords = nature (Clic here for more details about this article) |
2/3. Morquio-B disease, spondyloepiphyseal dysplasia associated with acid beta-galactosidase deficiency. Report of three cases in one family.Two sisters and one brother, all with normal intelligence and no evidence of neurological abnormality, present progressive spondyloepiphyseal dysplasia, stunted growth, corneal opacities, and increased keratansulfaturia. Cultured skin fibroblasts from one of the children showed a remarkable deficiency of acid beta-galactosidase in association with normal activities of N-acetylgalactosamine-6-sulfate sulfatase and sialidase. Acid beta-galactosidase was also deficient in leukocytes of two children. leukocytes of the parents exhibited intermediate activities, which suggests the primary nature of beta-galactosidase deficiency. patients with MPS IV-B may be severely affected.- - - - - - - - - - ranking = 1keywords = nature (Clic here for more details about this article) |
3/3. Upper airway obstruction during head flexion in Morquio's disease.Previous reports of pulmonary function in patients with Morquio's disease have emphasized the restrictive nature of their ventilatory defect. We describe a patient in whom pulmonary disability was secondary to upper airway obstruction from collapse of the trachea during head flexion. The same phenomenon was demonstrated in one of two other patients with Morquio's disease, both of whom were asymptomatic. Positionally dependent airway obstruction may be an important cause of pulmonary disability in Morquio's disease.- - - - - - - - - - ranking = 1keywords = nature (Clic here for more details about this article) |