Mucolipidosis II and III alpha/beta are genetic disorders caused by mutations in the GNPTAB gene. These conditions belong to a group of lysosomal storage disorders, where the lysosomes (cellular digestive system) don’t work properly due to a missing enzyme called GlcNAc-1-phosphotransferase.
Babies with Mucolipidosis II have limited growth, skeletal issues, coarse facial features, thick gums, joint stiffness, malformed bones, small head, and severe learning difficulties. It is severe, often leading to heart problems and breathing issues, causing death in early childhood.
Mucolipidosis III alpha/beta appears around age 3, causing slowed growth, shorter height, less prominent coarse facial features, joint stiffness, but normal intelligence. Mobility might decrease over time. It is less severe than mucolipidosis II; while heart and breathing problems still occur, affected individuals usually live into early to mid-adulthood. There is no cure for these conditions. Management involves therapies like occupational and speech therapy. Pamidronate might help with bone density and joint pain in mucolipidosis III alpha/beta, but it’s not a cure. Surgeries are generally avoided to prevent complications related to anesthesia and airways.
As noted above, this group of conditions is caused by pathogenic (disease-causing) variants in the GNPTAB 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.
Resources:
International Society for Mannosidosis and Related Disorders
Medline Plus (Mucolipidosis II alpha/beta)
Medline Plus (Mucolipidosis III alpha/beta)
Revised October 2023
