Muscle-eye-brain disease (MEB) is a type of congenital muscular dystrophy. It is characterized by the degeneration of muscles that help in movement (skeletal muscles), vision abnormalities, and delayed brain development.

Genetic mutations in MEB

MEB is a genetic condition caused by a mutation in the POMBGNT1  gene, which carries the instructions necessary to make an enzyme called O-linked mannose N-acetylglucosaminyltransferase 1. The role of this enzyme is to activate alpha-dystroglycan by adding a sugar molecule to it, a process called glycosylation.

Alpha-dystroglycan is a protein that provides structural support to the cells in skeletal muscles and directs the movement of nerve cells in the brain during early stages of development. Glycosylation of alpha-dystroglycan is vital for the protein to perform its function efficiently.

Mutations in POMGNT1 cause the O-linked mannose N-acetylglucosaminyltransferase 1 enzyme not to work properly. As a result, alpha-dystroglycan is not glycosylated. This affects its function and leads to the symptoms associated with MEB.

Inheritance of MEB causing mutations

Every cell in the human body has 23 pairs of chromosomes that carry a string of genes. Each parent contributes one chromosome to every pair. Of the 23 chromosomes,  22 are called autosomes, and one pair is the sex chromosome that determines an individual’s gender. There are two copies of every gene on the autosomes, one inherited from each parent.

The POMGNT1 gene is located on chromosome 1, an autosome. Therefore, there are two copies of the POMGNT1 gene in every individual. MEB is inherited in an autosomal recessive manner, meaning that both copies of the POMGNT1 gene must be mutated for the disease to develop.

A person with one copy of the mutated gene is called a carrier, and he or she may not show any symptoms. A couple where both individuals are carriers has a 25 percent chance of either having a child with MEB or a healthy child who does not inherit the mutation. They have a 50 percent chance of having a child who is also a carrier of MEB.

Genetic testing can be used to detect these mutations. Genetic counselors can explain the inheritance pattern of this mutation to help couples make informed health and family decisions.

 

Last updated: Aug. 26, 2019

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Muscular Dystrophy News is strictly a news and information website about the disease. It does not provide medical advice, diagnosis, or treatment. This content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified healthcare providers with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on this website.

Vijaya Iyer is a freelance science writer for BioNews Services. She has contributed content to their several disease-specific websites, including cystic fibrosis, multiple sclerosis, muscular dystrophy, among others. She holds a PhD in Microbiology from Kansas State University, where her research focused on molecular biology, bacterial interactions, metabolism, and animal models to study bacterial infections. Following the completion of her PhD, Dr. Iyer went on to complete three postdoctoral fellowships at Kansas State University, University of Miami and Temple University. She joined BioNews Services to utilize her scientific background and writing skills to help patients and caregivers remain abreast with important scientific breakthroughs.
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Özge has a MSc. in Molecular Genetics from the University of Leicester and a PhD in Developmental Biology from Queen Mary University of London. She worked as a Post-doctoral Research Associate at the University of Leicester for six years in the field of Behavioural Neurology before moving into science communication. She worked as the Research Communication Officer at a London based charity for almost two years.
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Vijaya Iyer is a freelance science writer for BioNews Services. She has contributed content to their several disease-specific websites, including cystic fibrosis, multiple sclerosis, muscular dystrophy, among others. She holds a PhD in Microbiology from Kansas State University, where her research focused on molecular biology, bacterial interactions, metabolism, and animal models to study bacterial infections. Following the completion of her PhD, Dr. Iyer went on to complete three postdoctoral fellowships at Kansas State University, University of Miami and Temple University. She joined BioNews Services to utilize her scientific background and writing skills to help patients and caregivers remain abreast with important scientific breakthroughs.
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