What is Morquio Syndrome?
Morquio syndrome (MPS IV) is a metabolic disorder and a type of mucopolysaccharidosis and is an inherited autosomal recessive mucopolysaccharides storage disease. This is a type of birth defect, which is very rare. In this condition, the body is not able to synthesize some types of mucopolysaccharides, which causes them to be eliminated or accumulate in the blood, bone marrow, cardiac system, respiratory system and other organs in the body resulting in progressive damage to the tissues, cells and organs producing various types of symptoms. Patients suffering from Morquio syndrome have distinctive skeletal deformities during childhood and suffer from short spine dwarfism. Morquio syndrome is characterized by excretion of abnormal quantities of keratin sulfate through urination and infiltration of keratin sulfate to the tissues. Morquio Syndrome is also known by other names, such as MPS IV, Beta galactosidase deficiency, Galactosamine-6-sulfatase deficiency, Mucopolysaccharidosis type IVA and Mucopolysaccharidosis type IVB.
Types of Morquio Syndrome
Morquio Syndrome Type A: This is the more common type of Morquio syndrome and it does not have sufficient N-acetylgalactosamine-6-sulfate sulfatase.
Morquio Syndrome Type B: This is the milder form of Morquio syndrome and exhibits lesser symptoms. In this type, there is insufficient production of beta-galactosidase.
Causes of Morquio Syndrome
Morquio syndrome is a condition, which is autosomal recessive trait. If both the parents have the faulty gene, which is associated with Morquio Syndrome, then their individual children will have about a 25% chance of having this syndrome.
As mentioned before there are 2 types of Morquio Syndrome: Type A, which does not produce sufficient enzyme galactosamine-6-sulfatase; and Type B, which does not produce sufficient enzyme beta-galactosidase.
Both these enzymes are important for the body to break down keratin sulfate sugar chain, which is a long strand of sugar molecules. In both Type A & B of Morquio syndrome, there is accumulation of extraordinary large amounts of glycosaminoglycans in the body, which causes damage to the organs. Morquio syndrome is estimated to affect 1 in every 200,000 babies. Children usually start experiencing symptoms between the ages of 1 and 3. Having a family history of Morquio syndrome increases the risk for having this condition.
Signs & Symptoms of Morquio Syndrome
Morquio Syndrome is not obvious until the child starts walking and given below are some of the important characteristics or signs of this condition:
- There is abnormal development of the skeletal system with deformity of the spine, where there is pointed kyphosis in the lower back, which can be misdiagnosed as gibbus deformity.
- The child with Morquio Syndrome has a waddling gait when walking.
- Morquio Syndrome patient also has symptoms of atlanto-axial instability where the ligaments holding the first two vertebrae on the neck become very lax and the head is also very large in size (macrocephaly).
- The patient’s height is also below average for his/her age with short stature and specifically a short trunk.
- The neck is also abnormally short along with short bones in the leg and forearms in patients with Morquio Syndrome.
- The fingers and toes are stubby in appearance.
- There is joint hypermobility and the child also has bowlegged knees or knocked knees.
- The teeth are widely spaced and the facial features of the patient are coarse.
- The ribs are wide in shape and the chest is bell-shaped.
- There is clouding of the cornea.
- There is early onset of degenerative joint disease.
- Morquio Syndrome patient also has cardiomegaly, heart murmur and mild hepatosplenomegaly.
- Inguinal hernia is also present.
Treatment of Morquio Syndrome
Symptomatic treatment is done for Morquio syndrome, as there is no particular treatment for this disease. Research is going on for a treatment which involves enzyme replacement therapy. As this is a hereditary condition, genetic counseling is recommended for parents with family history of Morquio syndrome. Osteotomy can be done to improve the gait of the patient by correcting the leg alignment. Spinal fusion is done to prevent permanent injury to the spinal cord and to prevent further deformities to the spine in patients with underdeveloped neck bones. It is important to learn how to properly position and handle the child for improved breathing, preventing contractures and preventing subluxation. Magnetic Resonance Imaging (MRI) scan helps in checking the stability of the neck.
Facts about Morquio Syndrome
Fact-1: Morquio Syndrome is a rare genetic condition.
Fact-2: Both males and females are equally affected by Morquio Syndrome.
Fact-3: Having a family history of Morquio Syndrome increases the risk of having this condition.
Fact-4: It is estimated that about 1 in 200,000 births will have Morquio Syndrome.
Fact-5: The affected child will appear normal at birth; however, as he/she grows, skeletal deformities will become evident.
Fact-6: Atlantoaxial instability is the primary concern, which leads to damage to the spinal cord resulting in paralysis or motor and sensory impairment.
Fact-7: Patients with Morquio Syndrome will have normal mental development or very mild mental impairment.
Fact-8: Various laboratory and diagnostic investigation are done during the first year of the child’s life, as that is the time when the symptoms become obvious.
Fact-9: The chief lab investigation, which is done, is urine test which will help in determining the presence of mucopolysaccharides, however, will not definitely determine the exact form of this condition.
Fact-10: X-ray of the long bones and spine, genetic testing, and ECG and ultrasound help in diagnosing Morquio Syndrome.
Fact-11: Other problems, such as cardiorespiratory complications, heart murmurs and trouble with breathing interferes with the child’s ability to do his/her activities.
Fact-12: It is important to get genetic counseling for parents who have a family history of Morquio syndrome and for parents who have a child with Morquio syndrome.
Counseling helps in the understanding of this disease and the possible treatments. Prenatal testing can also be done.
Life Expectancy & Prognosis of Patients with Morquio Syndrome
The life expectancy and prognosis of patients suffering from Morquio Syndrome is not good. Death eventually occurs for the patient due to compression of the spinal cord and cardiorespiratory failures. The life expectancy of patients with Morquio Syndrome is around approximately 30 years with some patients dying as early as 2 to 3 years of age. Some patients can also live up to 60 years with good care. It is important that this condition is detected early, as early detection and immediate treatment/intervention helps in bettering the patient’s quality of life and increasing the life expectancy of the patient.