What is Morquio syndrome?
Morquio syndrome is a rare inherited birth defect that is estimated to occur in one of every 200,000 births. The disease may not be visible at birth; symptoms usually begin between ages 1 and 3. Morquio syndrome is a progressive disease, meaning symptoms get worse as a child grows.
Morquio syndrome is part of a group of diseases called mucopolysaccharidosis (MPS). Morquio is also known as MPS IV.
In children with Morquio syndrome, the body cannot break down sugar chains called glycosaminoglycans that help build bone, cartilage, eye corneas, skin and connective tissue (such as tendons, ligaments, etc.)
People with glycosaminoglycans diseases either do not produce enough of the enzymes needed to break sugar chains into simpler molecules, or they produce enzymes that do not work normally. As a result, glycosaminoglycans collect in cells, blood and connective tissue and cause damage over time. There are two types of Morquio syndrome:
- Type A, in which an enzyme called galactosamine-6-sulfatase is missing
- Type B, in which there isn’t enough of the enzyme beta-galactosidase
The damage caused by the lack of either of these enzymes affects a child’s appearance, organ function and physical abilities. Children may develop:
- A pronounced curvature of the spine (i.e. scoliosis or kyphosis)
- Cloudy corneas of the eyes
- A heart murmur
- Inguinal hernia
- Liver enlargement
- Loss of nerve function below the neck
Several different syndromes occur as a result of the inability to break down glycosaminoglycans, including Hurler syndrome.
Morquio syndrome is an autosomal recessive trait, which means both parents must carry the gene that causes Morquio for a child to have the disorder.
Signs and symptoms
Symptoms of Morquio syndrome include:
- Short stature, with a very short torso
- Abnormal bone and spine development, including severe scoliosis
- Bell-shaped chest with ribs flared out at the bottom
- Hypermobile joints (joints that are very easy to bend in unusual positions, such as being able to bend the knees behind the head; sometimes called “double-jointed.”)
- Knock-knees (knees that point inward and touch each other as the person walks)
- Large head
- Widely-spaced teeth
- Coarse facial features which may include prominent scalp veins, flat-bridged nose and bulging forehead
- Possible heart and vision problems
Testing and diagnosis
Diagnostic evaluation usually begins with a thorough medical history and physical examination of your child. At Children’s Hospital of Philadelphia (CHOP), clinical experts use a variety of diagnostic tests to diagnose Morquio syndrome and possible complications, including:
- Genetic testing, in which a sample of your child’s saliva or blood is used to identify any abnormalities in your child’s DNA.
- X-rays, which produce images of bones
- Magnetic resonance imaging (MRI), which uses a combination of large magnets, radiofrequencies and a computer to produce detailed images of organs and structures within the body
- Echocardiogram, a test that determines the structure of the heart and how well it is functioning
- Skin fibroblast culture, in which a small piece of skin is removed during a short surgical procedure, then tested to see how collagen and other skin substances are functioning
- Eye exam and hearing test
- Blood and urine tests
Morquio syndrome is treated in many ways, because the condition can affect several body systems. The treatment a child needs depends on the severity of his symptoms. Some children might only require careful monitoring. Others may need non-surgical or surgical treatments to address specific aspects of their condition. Every child’s condition is different, so treatment is determined on a case-by-case basis.
At Children’s Hospital of Philadelphia, we practice collaborative, family-centered care. A team of expert clinicians — including leading physicians, pediatric nurses, physical and occupational therapists, psychologists and other specialists — will partner with you in the care of your child.
Many children with Morquio syndrome are diagnosed with orthopaedic conditions including: scoliosis, kyphosis, skeletal dysplasia, narrow chest, joint conditions and leg deformities. In some cases, these conditions are present at birth and can be treated when the child is very young.
In other cases, the complications from Morquio syndrome may only become evident — or problematic — as your child grows. This is often true for spinal deformities, limb deformities and joint issues.
For example, if your child has scoliosis, our team of specialists will consider the severity of the curve, where it occurs in the spine, and your child's age and stage of growth, before determining the best course of action. Treatment for scoliosis may include non-surgical options such as bracing and physical therapy, or surgical options such as spinal fusion or implanting growing rods to stabilize your child’s spine as he continues to grow.
Your child with Morquio syndrome will likely need to see several specialists throughout childhood and adolescence. At CHOP, we have expert physicians in every pediatric specialty. We offer follow-up care, ongoing support and services at our Main Campus and throughout our CHOP Care Network. Our team is committed to partnering with parents and referring physicians to provide the most current, comprehensive and specialized care possible for your child.
If your family has a history of Morquio syndrome, genetic counseling is recommended — especially if you are considering having more children.
Long-term outcomes for children with Morquio syndrome vary from child to child. Most children with Morquio syndrome have normal intelligence.
Children with spine and bone conditions can have difficulty walking and may require a wheelchair; others may be more mobile. Some children have ongoing breathing, vision or cardiac issues that may become more serious in adulthood.
Current research into treatments for Morquio syndrome includes:
- Enzyme replacement therapy
- Gene therapy
- Allogenic bone marrow transplantation
If successful, enzyme or gene therapy would replace or supplement missing enzymes.