GNAQ

GLB1

GLB1 is a gene that encodes the enzyme beta-galactosidase-1, which is crucial in the metabolism of certain carbohydrates. This enzyme is involved in the breakdown of complex molecules into simpler ones, a process essential for normal cellular function. Mutations in the GLB1 gene can lead to a variety of disorders, most notably GM1 gangliosidosis and Morquio syndrome type B.

Function

The GLB1 gene provides instructions for producing the enzyme beta-galactosidase-1. This enzyme is located in the lysosomes, which are compartments within cells that digest and recycle different types of molecules. Beta-galactosidase-1 is responsible for breaking down a molecule called GM1 ganglioside, as well as other molecules such as keratan sulfate.

Clinical Significance

Mutations in the GLB1 gene can lead to a deficiency of beta-galactosidase-1, resulting in the accumulation of GM1 ganglioside and other substances in the body. This accumulation can cause damage to cells, particularly in the brain, leading to the symptoms of GM1 gangliosidosis.

GM1 Gangliosidosis

GM1 gangliosidosis is a rare genetic disorder characterized by progressive neurological deterioration. It is classified into three types based on the age of onset and severity of symptoms: infantile, juvenile, and adult. Symptoms may include developmental delay, seizures, and skeletal abnormalities.

Morquio Syndrome Type B

Morquio syndrome type B is another disorder caused by mutations in the GLB1 gene. It is a type of mucopolysaccharidosis, specifically MPS IVB. This condition primarily affects the skeleton, leading to short stature, joint abnormalities, and other skeletal deformities.

Genetic Mutations

Over 100 mutations in the GLB1 gene have been identified. These mutations can be missense, nonsense, insertions, deletions, or splice site mutations. The type and location of the mutation can influence the severity of the disease.

Diagnosis and Testing

Diagnosis of disorders related to GLB1 mutations typically involves genetic testing to identify mutations in the GLB1 gene. Enzyme assays to measure beta-galactosidase activity in blood or fibroblasts can also be used.

Treatment

Currently, there is no cure for disorders caused by GLB1 mutations. Treatment is supportive and symptomatic, focusing on managing symptoms and improving quality of life. Research into enzyme replacement therapy and gene therapy is ongoing.

Also see

• Lysosomal storage disease
• Enzyme replacement therapy
• Genetic testing
• Mucopolysaccharidosis