Mucolipidosis III gamma is a disorder that occurs when people are missing an enzyme called GlcNAc-1-phosphotransferase, which is essential for the proper working of lysosomes—these are like the cell’s digestive system.
The main problems linked with mucolipidosis III gamma are related to the bones and joints, and they slowly appear as a person grows. Early signs, usually showing up in childhood, include stiffness, reduced flexibility, and pain in the joints—especially in the fingers, shoulders, and hips. Other bone issues involve slow growth, shorter height, weaker bones that may be prone to fractures, a curved spine (scoliosis), and slight changes in facial features. Additional symptoms can include heart valve problems, issues with the ribs that might affect breathing, and cloudiness in the cornea of the eyes. Many people with this condition will develop distinctive facial features, like a broad nose, large tongue, and thick lips. Most individuals have normal intelligence, but some may have mild intellectual disabilities. Unfortunately, there is no cure for mucolipidosis III gamma, and there are no known treatments to stop the joints from getting stiffer over time. Treatment options may include managing pain and physical therapy. In certain cases, surgery might be needed for procedures like hip or heart valve replacements.
Mucolipidosis III gamma is caused by pathogenic (disease-causing) variants in the GNPTG gene and exhibits autosomal recessive inheritance. This means that both parents must be carriers to have a 25% chance to have a child with the condition. The risk of being a carrier is based on a person’s ancestry or ethnic background.
Other names for this condition are mucolipidosis IIIC and pseudo-Hurler polydystrophy.
Resources:
International Society for Mannosidosis & Related Disorders
Revised November 2023
