Mucopolysaccharidosis IV (MPS IV) is a rare, progressive health condition caused by gene abnormalities. Although a metabolic disorder, it mainly affects the patient’s skeletal structure, resulting in stalled growth and bone malformations. The disease is also called Morquio Syndrome.
Mucopolysaccharidosis IV manifests as two types- Type A and Type B, based on the type of gene mutation that underlies the condition. These types cannot be differentiated based on the symptoms displayed. The disease indicators and their severity vary from person to person.
Signs and Symptoms
In MPS IV patients, the onset of illness starts early in childhood, between one and three years. By 18 months, the physical growth starts to slow down, and it completely stops around eight years of age. The main symptoms include:
1. Skeletal Abnormalities- Shortened long bones resulting in the short physical build-up, bell-shaped chest, knock knees, spine curvature, dysplasia or abnormal cell growth of hips, wrists, or waist, and hypermobility or restricted movement of joints.
2. Underdeveloped Odontoid Process (Odontoid Hypoplasia)¬- Odontoid process is a peg-like bone in the neck, which aids in the lateral rotation of cervical vertebrae. A major sign of Mucopolysaccharidosis IV is a malformed odontoid process resulting in a condition called odontoid hypoplasia, which could lead to misalignment of the cervical spine resulting in damage to the spinal cord.
3. Vision And Auditory Issues- Cloudy cornea resulting in loss of vision, frequent ear infections, and loss of hearing are common symptoms.
4. Heart, Pulmonary, and Hepatic Issues¬- MPS IV patients may suffer from heart valve abnormalities or moderately enlarged liver. In some people, the lungs could become congested, causing frequent upper respiratory tract infections (URTI) and sleep apnea.
5. Symptoms Related to Physical Appearance- Persons with MPS IV will have slightly coarse facial features like a protruded forehead or a prominent lower face. Patients suffer from weakened tooth enamel and multiple cavities. Other physical deformities include a softly protruding belly button (umbilical hernia) or bulged lower abdomen.
Growth delays,A prominent lower face,Abnormal sideways and front-to-back or side-to-side curvature of the spine (kyphoscoliosis) or concern for a spine abnormality,An abnormally short neck,Knees that are abnormally close together (knock knees or genu valgum),Flat feet,Abnormal development of the growing ends of the long bones (epiphyses),Hip dislocation and arthritis and/or a prominent breast bone (pectus carinatum),Hearing loss, Weakness of the legs, and/or additional abnormalities may also occur
Group of inherited lysosomal storage disorders
Enzyme replacement therapy (elosulfase alfa, or Vimizim),Surgery