Overcoming the barriers to diagnosis of Morquio A syndrome
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RESEARCH
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Overcoming the barriers to diagnosis of Morquio A syndrome Kaustuv Bhattacharya1, Shanti Balasubramaniam2, Yew Sing Choy3, Michael Fietz4, Antony Fu5, Dong Kyu Jin6, Ok-Hwa Kim7, Motomichi Kosuga8, Young Hee Kwun6, Anita Inwood9, Hsiang-Yu Lin10, Jim McGill9, Nancy J Mendelsohn11, Torayuki Okuyama8, Hasri Samion12, Adeline Tan13, Akemi Tanaka14, Verasak Thamkunanon15, Teck-Hock Toh16, Albert D Yang17 and Shuan-Pei Lin10*
Abstract Background: Morquio A syndrome is an autosomal recessive lysosomal storage disease often resulting in lifethreatening complications. Early recognition and proficient diagnosis is imperative to facilitate prompt treatment and prevention of clinical complications. Methods: Experts in Asia Pacific reviewed medical records focusing on presenting signs and symptoms leading to a diagnosis of Morquio A syndrome. Results: Eighteen patients (77% female) had a mean (median; min, max) age of 77.1 (42.0; 0.0, 540.0) months at symptom onset, 78.9 (42.0; 4.5, 540.0) months at presentation and 113.8 (60.0; 7.0, 540.0) months at diagnosis. Orthopedic surgeons and pediatricians were most frequently consulted pre-diagnosis while clinical geneticists/ metabolic specialists most frequently made the diagnosis. Delayed diagnoses were due to atypical symptoms for 5 patients (28%), while 4 patients (22%) experienced each of subtle symptoms, symptoms commonly associated with other diseases, or false-negative urine glycosaminoglycan analysis. Two patients (11%) each experienced overgrowth within the first year of life. Two patients with Morquio A syndrome (11%) were diagnosed with craniosynostosis and 1 (6%) for each of Legg-Calv?-Perthes disease, Leri-Weill syndrome, and pseudoachondroplasia. Early radiographic features of Morquio A syndrome led to more efficient diagnosis. Conclusions: Increased awareness of clinical symptomology overlapping with Morquio A syndrome is essential. Clinicians encountering patients with certain skeletal dysplasia should consider Morquio A syndrome in their differential diagnosis. Atypical or subtle symptoms should not eliminate Morquio A syndrome from the differential diagnosis, especially for patients who may have non-classical phenotype of Morquio A syndrome. Keywords: Mucopolysaccharidosis, Morquio A syndrome, Diagnosis, Skeletal dysplasia, Asia Pacific
Background Morquio syndrome (mucopolysaccharidosis IV, MPS IV) is a rare autosomal recessive lysosomal storage disease that includes Morquio A and Morquio B [1]. Morquio A is characterized by a deficiency of the enzyme N-acetylgalactosamine-6-sulfatase (GALNS) while Morquio B is a distinct disease characterized by a deficiency of beta-galactosidase (GLB1). The reduced GALNS activity of Morquio A results in impaired catabolism of * Correspondence: [email protected] 10 Department of Pediatrics, Mackay Memorial Hospital, No. 92, Sec. 2, Zhongshan N. Road, Taipei City 10449, Taiwan Full list of author information is available at the end of the article
the glycosaminoglycans (GAGs) keratan sulfate (KS) and cho
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