Mucopolysaccharidosis type IVB


What is mucopolysaccharidosis type IVB?

Mucopolysaccharidosis type (MPS) IVB is a rare genetic disorder. This means that people have a problem in a specific gene. People have about 20,000-25,000 genes in their bodies. Genes are like our body's instruction manual - they control the growth, development and normal function of the body. Because of a change in a specific gene, people with MPS IVB lack an enzyme. This enzyme is needed to break down (metabolize) certain complex substances in the body. Without this enzyme, people cannot break down certain large sugar molecules. These molecules build up in the tissues, bones and major organs of the body. Eventually this damages the affected area and organs. People with MPS IVB can have lots of problems. They can have skeleton, heart, vision and dental problems, hearing loss, growth deficiency and short stature. People can have different symptoms and the symptoms that occur can be mild or severe. The brain is not affected and people usually have normal intelligence and generally have no issues with thinking or learning. However, some children can have delays in reaching developmental milestones or learning disabilities because of certain symptoms, particularly spinal problems, related to this disorder. There are two types of MPS IV: type IVA and type IVB. Type IVA is caused by alterations (mutations) in the GALNS gene. Type IVB is caused by alterations in the GLB1 gene. Generally, children with MPS IVB have less severe symptoms than children with MPS IVA, but this is not always the case as the severity of these disorders can vary greatly among affected people.

SOURCE: Emory University - Department of Human Genetics in collaboration with ThinkGenetic • • DATE UPDATED: 2017-02-12


Froissart R, Marie I. Mucopolysaccharidosis type 4. OrphaNet website. Accessed February 2, 2016.

Regier DS, Tifft CJ. GLB1-Related Disorders. GeneReviews website. Accessed February 2, 2016.

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