[Heterogeneity of formes frustes of Morquio's disease]

Two children presenting with a mild form of Morquio's syndrome are reported. Clinically, there was a characteristic brevity of the trunk and slit lamp examination showed discrete corneal opacities. On X-ray films, generalized plastyspondylia was moderate but it was associated with hypoplasia of the odontoid process. Acetabula were enlarged with coxa valga; obliquity of inferior radio-cubital extremity was associated with a sharp pattern of the proximal end of metacarpi. Epiphyseal cartilage chondrocytes also looked like those of Morquio's syndrome: large cells containing numerous vacuoles, limited by a single smooth membrane. On the other hand, no keratosulfate was found in urines and N-acetylgalactosamine-6-sulfate-sulfatase and beta-galactosidase assays in fibroblasts were normal. Thus, this mild form is different from the so-called Morquio's syndromes types A and B.