Morquio‐like syndrome with beta galactosidase deficiency and normal hexosamine sulfatase activity: Mucopolysaccharidosis IVB

Abstract

A 14-year-old white girl with mild dysostosis multiplex, odontoid hypoplasia, short stature, cloudy corneas, keratansulfaturia, but without detectable central nervous system abnormalities was referred with the diagnosis of Morquio syndrome. Clinical and roentgenographic findings were minimal compared to those of typical patients with the Morquio syndrome, MPS IV. Beta-Galactosidase activity in extracts of the patient's cultured fibroblasts was deficient, while that of galactosamine-6-sulfate sulfatase was normal. Conjunctival biopsy revealed intracytoplasmic vacuoles typical of lysosomal storage diseases. It is postulated that in this patient the deficiency of a beta-galactosidase is responsible for inadequate degradation of keratan sulfate and the appearance of a mild form of the Morquio syndrome (MPS IVB).

Association of N-Acetylgalactosamine-6-sulfate Sulfatase with the Multienzyme Lysosomal Complex of β-Galactosidase, Cathepsin A, and Neuraminidase

“…KS accumulation, which occurs in both clinical forms of ␤-galactosidosis (27), is presently explained by the primary deficiency of GAL. However, this hypothesis still does not explain the accumulation of both undersulfated and normally sulfated forms of KS, since normal or low normal levels of GALNS activity are detectable in cultured cells from patients (26,27).…”

A review of the clinical presentation and diagnosis of Mucopolysaccharidosis IVA

“…In the follow-up study, Arbisser et al (1977) (48) described a similar case of mild MPS IVA-like symptoms in a patient with β-galactosidase deficiency, proposing an alternate description of the disease as MPS IVB. Since the description of MPS IVB in 1977 (48), MPS IV has been categorized as two types, which include MPS IVA (GALNS deficiency) and MPS IVB (β-galactosidase deficiency). The clinical manifestation of β-galactosidase deficiency include platyspondyly of the vertebrae, significant dysplasia of the long bones (femoral epiphyses), atlanto-occipital instability, distal epiphyses, genu valgum, gait abnormalities, and corneal clouding.…”

“…As well, GM-1 β-galactosidase activity may be sufficient to prevent peripheral nervous system disorders seen in MPS IVA. Arbisser et al (48) have described the symptoms of MPS IVB as being mild (less severe) relative to those observed in patients with MPS IVA; however, varying severities of MPS IVA have been proposed (7;16;17;23;29-31;50). The diagnosis and classification of MPS IVA disease severity will be discussed later in this manuscript.…”

Enfermedad de Morquio (mucopolisacaridosis IV-A): aspectos clínicos, diagnósticos y nuevo tratamiento con terapia de reemplazo enzimático

“…3 En 1976, se describió un caso compatible con enfermedad de Morquio, pero la enzima deficiente era la beta-galactosidasa ácida. 4 Esta situación fue corroborada por otro autor, 5 por lo que hoy se define la MPS IV en tipo A (deficiencia de GALNS) y tipo B (deficiencia de betagalactosidasa). 6 Con la aprobación por parte de la Administración de Medicamentos y Alimentos (Food and Drug Administration; FDA, por sus siglas en inglés) al inicio de 2014 de la terapia específica para la MPS IV-A, esta entidad ha generado un mayor interés en la comunidad médica.…”