Summary about Disease
Morquio syndrome, also known as mucopolysaccharidosis type IV (MPS IV), is a rare, inherited metabolic disorder caused by a deficiency in enzymes needed to break down certain complex sugar molecules called glycosaminoglycans (GAGs), specifically keratan sulfate and chondroitin-6-sulfate. This leads to an accumulation of these GAGs in various tissues and organs, causing a range of skeletal abnormalities, and other complications. There are two main types: Morquio A and Morquio B, depending on which specific enzyme is deficient.
Symptoms
Symptoms vary in severity but commonly include:
Skeletal Abnormalities: Short stature (dwarfism), spinal deformities (scoliosis, kyphosis), joint laxity, knock-knees (genu valgum), hip dysplasia, and chest deformities.
Other Physical Features: Coarse facial features, prominent sternum (pigeon chest), enlarged liver and spleen (hepatosplenomegaly), corneal clouding, and dental abnormalities.
Neurological Issues: Spinal cord compression due to skeletal abnormalities can lead to weakness, paralysis, or other neurological problems.
Respiratory Problems: Narrowed airways and chest deformities can cause breathing difficulties and increased susceptibility to respiratory infections.
Hearing Loss: Often progressive hearing impairment.
Heart Problems: Heart valve abnormalities may occur.
Causes
Morquio syndrome is caused by genetic mutations in genes that encode enzymes responsible for breaking down GAGs.
Morquio A: Mutations in the GALNS gene, which codes for the enzyme N-acetylgalactosamine-6-sulfatase.
Morquio B: Mutations in the GLB1 gene, which codes for the enzyme beta-galactosidase. It is inherited in an autosomal recessive pattern, meaning that both parents must carry a copy of the mutated gene for a child to be affected.
Medicine Used
Enzyme Replacement Therapy (ERT): Elosulfase alfa (Vimizim) is an ERT approved for Morquio A syndrome. It provides a synthetic version of the missing enzyme to help break down GAGs.
Supportive Care: Management of symptoms with pain medication, physical therapy, and surgeries to correct skeletal abnormalities.
Bisphosphonates: May be used to improve bone density.
Is Communicable
No, Morquio syndrome is not communicable. It is a genetic disorder, not an infectious disease. It cannot be spread from person to person.
Precautions
Since Morquio syndrome is a genetic condition, there are no specific precautions to prevent acquiring the disease. However, genetic counseling and testing can be helpful for families with a history of Morquio syndrome who are planning to have children. Individuals with Morquio syndrome should take precautions to manage and minimize the impact of their symptoms:
Regular Medical Checkups: Monitor progression of the disease and adjust treatment as needed.
Physical Therapy: Maintain joint mobility and muscle strength.
Avoid Activities that Strain Joints: Protect weakened joints from injury.
Respiratory Support: Manage respiratory issues and prevent infections.
Cardiac Monitoring: Regular checkups to monitor heart health.
How long does an outbreak last?
Morquio syndrome is not an infectious disease and therefore does not have outbreaks. It is a chronic, lifelong condition.
How is it diagnosed?
Diagnosis typically involves:
Clinical Evaluation: Physical examination and assessment of symptoms.
Urine Tests: Measurement of GAG levels (keratan sulfate) in urine.
Enzyme Assays: Measurement of enzyme activity in blood or cultured cells.
Genetic Testing: Identification of mutations in the GALNS or *GLB1* genes.
X-rays: Evaluation of skeletal abnormalities.
Echocardiogram: Evaluation of heart function
Timeline of Symptoms
Infancy/Early Childhood: Symptoms may be subtle initially. Height may be normal at birth, but growth slows down in early childhood. Skeletal abnormalities may become noticeable.
Childhood: Skeletal problems worsen, leading to short stature and deformities. Motor skills may be delayed. Other symptoms like corneal clouding and hearing loss may develop.
Adolescence/Adulthood: Symptoms continue to progress. Spinal cord compression may become a major concern. Respiratory and cardiac problems may develop or worsen. Life expectancy can be shortened depending on the severity of the condition.
Important Considerations
Multidisciplinary Care: Requires a team of specialists, including geneticists, orthopedic surgeons, cardiologists, pulmonologists, ophthalmologists, and physical therapists.
Spinal Cord Compression: Close monitoring for spinal cord compression is crucial, as it can lead to paralysis if left untreated.
Anesthesia Risks: Individuals with Morquio syndrome have unique risks associated with anesthesia due to airway abnormalities and spinal instability.
Psychosocial Support: The chronic nature of the disease and physical limitations can impact quality of life, making psychosocial support important for individuals and families.
Early Intervention: Early diagnosis and intervention can help manage symptoms and improve quality of life.