Morquio syndrome is a rare, inherited condition that affects bones, joints, and organs—progressively worsening over time. It typically begins in early childhood and can significantly impact growth and mobility. Early diagnosis and treatment are essential to improving quality of life and managing complications.
In this blog, you’ll discover everything you need to know about Morquio syndrome—what it is, what causes it, its symptoms, how it’s diagnosed, and the treatment options available.
What is Morquio Syndrome?
Morquio syndrome, also known as Mucopolysaccharidosis IV (MPS IV), is a rare genetic disorder that causes bone growth abnormalities and several other symptoms throughout the body that worsen with time.
It occurs when the body lacks specific enzymes needed to break down glycosaminoglycans (GAGs)—large sugar molecules that accumulate and cause cellular damage. There is currently no cure, but treatments can help manage symptoms and improve function.
In the United States, it is estimated to affect 1 in 200,000 people, and approximately 95% of cases are of type A.
Types of Morquio Syndrome
The following are the two types of Morquio syndrome, based on the enzyme deficiency that share the same symptoms, but have distinct genetic causes:
- MPS IVA (Type A): Caused by a deficiency of the GALNS enzyme (N-acetyl-galactosamine-6-sulfatase).
- MPS IVB (Type B): Caused by a deficiency of the GLB1 enzyme (beta-galactosidase).
Both types present similar symptoms, but require different treatments, making an accurate diagnosis crucial.
Causes of Morquio Syndrome
Morquio syndrome is caused due to genetic mutations (changes) in either GALNS or GLB1 genes that are required to break down glycosaminoglycans (GAGs). This, in turn, leads to the accumulation of GAGs in tissues, organs, and cells, contributing to progressive damage.
How does it occur?
- When genetic mutations target either of the genes, the enzymes do not have the instructions they require to perform the job, meaning they have less or no activity.
- The deficiency of these enzymes leads to the accumulation of sugar molecules in the lysosomes, the waste disposal system of the cells that break down or recycle the molecules.
- For this reason, Morquio syndrome is also called "lysosomal storage disorder".
- The sugar molecules basically accumulate in the tissues and organs, but significantly impact the bones, where the symptoms develop.
How is Morquio Syndrome Inherited?
The inheritance of this genetic disorder takes place in an autosomal recessive manner.
- This means that the child must receive a mutated gene (either the GALNS or GLB1 gene) from both parents to develop this disorder.
- Research reports that if both parents carry a defective gene, the chances of a child inheriting both genes and developing Morquio syndrome are 25%.
- So, if parents have a child with MPS IV, it is expected that they are carriers of the mutated genes.
Genetic counseling is strongly recommended for families with a history of this condition.
Potential Symptoms of Morquio Syndrome
The signs of Morquio disease typically start in early childhood, between 1 to 3 years of age. The common symptoms may include:
- Abnormal skeletal development (e.g., short stature, curved spine, and knock-knees)
- Enlarged chest and head
- Joint abnormalities and hypermobility
- Difficulty standing or walking
- Cloudy corneas & vision issues
- Heart and lung complications
- Ear infections and hearing loss
Severe symptoms:
- Airway blockages
- Compressed spinal cord (paralysis)
- Heart valve abnormalities
Note: Report these symptoms immediately to a doctor to prevent further complications.
When to See a Doctor?
The symptoms that impact the airways and spinal cord are most serious and need emergency medical attention. If your child can't move the body parts or has trouble breathing, visit the emergency room. Also, consult the pediatrician if your child experiences:
- Pain
- Swelling
- Clear to yellow fluid draining from the surgical site
- fatigue, abnormal posture, or delayed milestones appear.
Possible Complications
If left untreated, Morquio disease can lead to the following complications that can be life-threatening:
- Breathing problems
- Heart failure
- Spinal cord damage
- Possible paralysis
- Vision problems like corneal clouding
- Enlarged spleen and liver
- Severe walking difficulties
Diagnosis of Morquio Syndrome
The diagnosis often begins during early childhood as symptoms begin to become apparent. The healthcare providers will do a physical exam to examine the symptoms. In addition, they recommend the following diagnostic tests:
- Urine test: To evaluate the excess levels of glycosaminoglycan.
- Blood enzyme test: To find out whether a gene is responsible for the developed symptoms and the enzyme activity in the body.
- Genetic testing: Confirms the diagnosis, identifies carriers, and supports prenatal diagnosis.
- X-rays: To examine bone structures to detect any bone-related abnormalities.
- MRIs: To get detailed images of the brain and spinal cord to identify any deformities.
Treatment Options for Morquio Syndrome
There is no cure for Morquio syndrome, however, many treatment options are available to manage the symptoms. Those treatment options are:
1. Enzyme Replacement Therapy (ERT)
- Uses a medicine called elosulfase alfa (Vimizim) that is administered intravenously to replace the missing enzyme GALNS, which is important for breaking down large sugar molecules in the body.
- This thus reduces the accumulation of chondroitin-6-sulfate & keratan sulfate that causes Morquio syndrome symptoms.
2. Physical Therapy
- Maintains and improves strength, balance, movement, coordination, and overall function.
- This helps you to perform age-specific activities and maintain self-dependence.
3. Surgical Interventions
Crucial for managing the impact of Morquio disease on airways, the musculoskeletal system, and other areas. Those include:
- Spinal Decompression & Fusion: Treats skeletal abnormalities by relieving pressure on the spinal cord and stabilizing it.
- Hip Reconstruction & Replacement: Reconstruction involves cutting & shaping the affected bones in the hip socket and thigh bone to improve joint stability and alignment. On the other hand, replacement helps replace the damaged joint surfaces with artificial ones to relieve pain and restore joint function.
- Leg Osteotomies: Fix the alignment of the thigh bone (femur) and shin bone (tibia) to treat knock-knees (genu valgum), improve gait (walking manner), and alleviate pain.
- Cornea replacement (penetrating keratoplasty): Treat corneal opacification (a clouding in the cornea) by replacing the damaged cornea with a healthy one, which improves vision.
4. Hearing Aids & Ear Tubes:
- Bone Conduction Hearing Aids to manage conductive hearing loss associated with ossicle deformities and middle ear fluid caused by Morquio syndrome.
- Traditional Hearing Aids to manage sensorineural hearing loss that impacts the inner area of ear.
- Tympanostomy Tubes drain out fluid from the middle ear, which is responsible for causing conductive hearing loss.
5. Cardiac & Pulmonary Monitoring
- Involves regular assessments, like electrocardiograms (ECGs) to identify and manage complications such as cardiac valve disease, irregular heartbeats, or heart rhythm abnormalities.
- Also, it includes annual pulmonary function tests to detect respiratory impairments or check lung function.
Can Morquio Syndrome Be Prevented?
No, Morquio syndrome is not preventable as it is a genetic disorder. Schedule an appointment with the healthcare provider about genetic testing to know about the risk of having a child with such a condition. Also, they can help with genetic counseling for couples to make informed decisions about family planning and their health if they have a family history of Morquio syndrome.
Life expectancy for Morquio syndrome
The life expectancy of individuals with Morquio syndrome varies depending on the severity and type of the disease, and access to treatment.
- People with severe symptoms, especially of Morquio A, might not live beyond the age of 20 or 30.
- Individuals with mild symptoms can live into middle adulthood or even exceed 70 years.
- The less severe cases may lead to a lifespan longer than 70 years.
- Symptoms that lead to death are respiratory failure, heart valve disease, and spinal cord compression.
Overall, this genetic disease can significantly affect life expectancy, however, improved understanding of the condition and advanced treatments can contribute to a longer and better quality of life.
How Can Parents Support a Child with Morquio Syndrome?
As Morquio syndrome begins in early childhood, parents can make their children aware of the disease and address associated challenges. To help the children:
- Teach them about Morquio syndrome.
- Attend all their necessary medical appointments.
- Note down their symptoms, treatment, and visits.
- Find the best ways for them to adapt. For instance, ask the school staff to make the same changes, like foot support and lower chairs, and also ensure the child receives all the crucial support.
- Seek guidance from orthopedists, pulmonologists, genetic counselors, and all other specialists who can provide child care and support.
- Encourage hobbies that can enhance their quality of life and boost confidence.
- Teaching them about bullying and teasing is not okay, and also work with school staff members to take care of such issues.
- Nurture a positive attitude in children so that they can cope with the living challenges associated with Morquio disease.
- Also, parents need to take care of themselves to provide the best care and support to their children.
Summing Up
While Morquio Syndrome or Mucopolysaccharidosis IV (MPS IV) is a rare and lifelong genetic disorder, early diagnosis and effective treatment can improve health and quality of life. With advanced therapies and surgeries and growing awareness, one can receive better support. When you experience any symptoms, report them immediately to your doctor, as it can help prevent further complications that can be life-threatening.
FAQs
Does Morquio syndrome affect intelligence?
No, it does not affect intelligence; people maintain normal intellectual capacity.
Is Morquio a form of dwarfism?
Yes, it's a form of dwarfism, particularly skeletal dysplasia, which is marked by short stature or other skeletal abnormalities.
Who is most likely to get Morquio syndrome?
Children with parents carrying the mutated genes, people with a family history of this condition, or individuals from specific ethnic groups like German, Swedish, and Turkish.
How tall are people with Morquio syndrome?
The final height of people with Morquio disease is 87 cm (94-125 cm).
What are the facial features of mucopolysaccharidosis?
They include a prominent forehead, mild coarse facial features, thick eyebrows and hair, and a large head. Some individuals have a short stature.
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