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Morquio A?
Long perceived as an orthopedic condition, Morquio A
is a progressive disease that impacts major organ systems.1-3
Mucopolysaccharidosis IVA (MPS IVA), or Morquio A, is an autosomal recessive lysosomal storage disorder that, while commonly perceived as a musculoskeletal condition, is in fact a progressive, multisystemic disease. The root cause of Morquio A is an inherited deficiency in the N-acetylgalactosamine-6-sulfatase (GALNS) enzyme, which has been shown to lead to systemic morbidities and a shortened life span.1-3 GALNS is a critical lysosomal enzyme that, when inactive or deficient, drives a cascade of progressive metabolic pathologies that affect major organ systems.2,4-8
The signs and symptoms of Morquio A may initially present as musculoskeletal complications but progressively manifest throughout the body, with potentially severe cardiovascular, pulmonary, neurological, skeletal, rheumatologic, ophthalmologic, ENT, hepatic, and dental consequences.1,4,9-23
In addition to systemic organ involvement, patients with Morquio A suffer from dramatically impaired functional capacity, severely limiting their potential.9
Morquio A syndrome (MPS IVA) is a lysosomal storage disorder caused by a mutation in the gene encoding the enzyme N-acetylgalactosamine-6-sulfatase (or GALNS). In Morquio A syndrome, defective GALNS enzyme activity impairs lysosomal degradation of the glycosaminoglycans keratan sulfate and chondroitin-6-sulfate.1,7,22,24
As lysosomes accumulate, they occupy an increasingly greater area of the cytoplasm, obscuring other organelles and disrupting function. The defective enzyme activity in Morquio A syndrome leads to cell, tissue, and organ system dysfunction that results in the progressive multisystemic morbidities that are the hallmark of this disorder.22,24,25
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Bank et al, Mol Genet Metab, 2009 | Bank et al, Mol Genet Metab, 2009 |
Deficient GALNS enzyme activity can lead to progressive organ damage resulting in complex manifestations with life-altering consequences across multiple organ systems.1-3
Together, multisystemic consequences severely impact functional outcomes for Morquio A patients and their families, affecting almost every aspect of life.9 These outcomes may be measured clinically through endurance functional tests such as the 6-minute walk test (6MWT) and the 3- minute stair climb (3MSC), as well as by respiratory function tests such as forced vital capacity (FVC) and maximum voluntary ventilation (MVV).9 Learn more about the natural history of Morquio A.
6MWT is a commonly used measure of the integrative functional capacity of multiple organ systems, such as cardiopulmonary competence and musculoskeletal function. 6MWT is routinely used across multiple disease states to assess endurance as a measure of integrative functional capacity in disorders as widely varying as cystic fibrosis, cardiovascular disease, and Morquio A.27
Place your cursor over each of the patient images below to see more detailed information.
The Morquio Clinical Assessment Program (MorCAP) is an ongoing longitudinal study of over 325 Morquio A patients from 15 sites in 10 countries, initiated in 2008. The baseline analysis reveals a spectrum of disease complications, with wide-ranging clinical effects.9
Cardiac involvement is common in MorCAP patients9
Nonskeletal involvement is common9
Spinal involvement is common in Morquio A9
Download the Morquio Clinical Assessment Program (MorCAP): Baseline Results slide deck.
Morquio A is an autosomal recessive, monogenic disorder resulting from mutations in the gene encoding N-acetylgalactosamine-6-sulfatase (GALNS).28
Morquio A is a genetically heterogeneous disorder with a high frequency of novel mutations reported.
As in other autosomal recessive disorders, molecular analysis, genetic counseling, and family screening are important components of familial risk assessment.