Mucopolysaccharidosis IVA (Morquio A syndrome) and VI (Maroteaux–Lamy syndrome): under-recognized and challenging to diagnose

Ralph S Lachman,Renée Shediac,Scott Hoffinger,Barbara K Burton,Christina Lampe,Klane K White,Dong-Kyu Jin,Pranoot Tanpaiboon,Lorne A Clarke,Nancy J Mendelsohn,Ok-Hwa Kim,Hiroki Kano,Shiro Ikegawa

doi:10.1007/s00256-013-1797-y

Abstract

ObjectiveMucopolysaccharidosis IVA (MPS IVA, or Morquio A syndrome) and VI (MPS VI, or Maroteaux–Lamy syndrome) are autosomal recessive lysosomal storage disorders. Skeletal abnormalities are common initial presenting symptoms and, when recognized early, may facilitate timely diagnosis and intervention, leading to improved patient outcomes. Patients with slowly progressing disease and nonclassic phenotypes can be particularly challenging to diagnose. The objective was to describe the radiographic features of patients with a delayed diagnosis of MPS IVA or VI.Materials and MethodsThis was a retrospective study. The records of 5 MPS IVA and 3 MPS VI patients with delayed diagnosis were reviewed. Radiographs were evaluated by a radiologist with special expertise in skeletal dysplasias.ResultsAn important common theme in these cases was the appearance of multiple epiphyseal dysplasia (MED) with epiphyseal changes seemingly confined to the capital (proximal) femoral epiphyses. Very few patients had the skeletal features of classical dysostosis multiplex.ConclusionsRadiologists should appreciate the wide phenotypic variability of MPS IVA and VI. The cases presented here illustrate the importance of considering MPS in the differential diagnosis of certain skeletal dysplasias/disorders, including MED, some forms of spondylo-epiphyseal dysplasia (SED), and bilateral Perthes-like disease. It is important to combine radiographic findings with clinical information to facilitate early testing and accurate diagnosis.

Highlights

Materials and methodsThe mucopolysaccharidoses (MPS) are lysosomal storage disorders caused by defects in glycosaminoglycan (GAG) catabolism [1] and are classified under the dysostosis multiplex group of skeletal dysplasias [2]
An important common theme in these cases was the appearance of multiple epiphyseal dysplasia (MED) with epiphyseal changes seemingly confined to the capital femoral epiphyses
We present 8 cases that highlight the challenges associated with diagnosing MPS IVA (Morquio A syndrome) and MPS VI (Maroteaux–Lamy syndrome), two MPS disorders for which enzyme replacement therapy (ERT) is available or in development [6, 7]

Summary

Introduction

Materials and methodsThe mucopolysaccharidoses (MPS) are lysosomal storage disorders caused by defects in glycosaminoglycan (GAG) catabolism [1] and are classified under the dysostosis multiplex group of skeletal dysplasias [2]. Many radiographic and clinical manifestations of MPS may mimic those of other skeletal dysplasias, further complicating the path to diagnosis. MPS VI is an autosomal recessive disorder caused by deficient activity of N-acetylgalactosamine 4-sulfatase (arylsulfatase B or ARSB), the enzyme that catabolizes dermatan sulfate [9]. Classic signs and symptoms include short stature, skeletal abnormalities with some of the characteristic radiographic changes of dysostosis multiplex, joint problems, respiratory complications, cardiac disease, ocular abnormalities, and hearing loss [8,9,10,11]. Individuals with more slowly progressive disease typically develop symptoms later in life and may present with more subtle disease manifestations, increasing the likelihood of a delayed or missed diagnosis [12,13,14,15]. Many MPS IVA and VI individuals are at risk of multisystem impairment and significant morbidity, underscoring the importance of early

Results

Discussion

Conclusion