What is MPS IVB?
Mucopolysarcharidosis type IVB (MPS IVB), also known as Morquio syndrome type B, is a rare, inherited disorder. MPS IVB is one of 50 diseases classified as lysosomal storage disorders (LSD), in which a genetic variation disrupts the normal activity of lysosomes in human cells.
What are lysosomes and what do they do?
Lysosomes contain specific proteins (enzymes) responsible for breaking down and recycling molecules such as fats and sugars. Individuals with a lysosomal storage disorder lack one of these necessary enzymes or do not have one of these enzymes in sufficient quantities to break down molecules for proper cell function.
Mucopolysarcharidosis Type IVB | Symptoms & Causes
What are the symptoms of MPS IVB?
Manifestations of MPS IVB fall on a broad spectrum, meaning children may or may not experience many of the condition’s associated symptoms. Children with MPS IVB generally do not experience or display symptoms at the time of their birth. Over time, they may develop skeletal abnormalities including:
- knock-knees (genu valgum)
- chest wall deformity (pectus carinatum)
- Legg-Calve-Perthes disease
- short stature
Over time, children may develop additional symptoms, including:
- sleep apnea
- hearing loss
- visual impairment/corneal clouding
- enlargement of the liver and spleen
- dental abnormalities
- thickening/impairment of the heart valves
- compression of the spinal cord
What causes MPS IVB in children?
MPS IVB is caused due to a deficiency in an enzyme known as beta-galactosidase. This condition is genetic and is inherited in an autosomal recessive pattern, which means that an affected child has received one defective copy of the gene responsible for beta-galactosidase production from each parent.
Mucopolysarcharidosis Type IVB | Diagnosis & Treatments
How do we treat MPS IVB?
There are currently no approved therapies that reverse the effects of MPS IVB. Current approaches to the disease involve interdisciplinary collaboration to provide supportive therapies and targeted management for specific symptoms of MPS IVB.
How we care for MPS IVB
At the Boston Children’s Lysosomal Storage Disorders (BoLD) Program, our team of providers is committed to the care of complex patients. As part of Boston Children’s Hospital, we are prepared to meet the challenge of providing multifaceted care by partnering with you and your child to deliver direct care in our BoLD clinic. We work with the broad array of world-class specialists at Boston Children’s to optimize the care we provide your child with MPS IVB.