What is GNE myopathy?
GNE myopathy is an inherited muscle condition where GNE is the name of the gene that codes for a protein called UDP-N-acetylglucosamine 2-epimerase/N-acetylmannosamine kinase. Several other names have previously been used to describe the same condition: hereditary inclusion body myopathy (HIBM); distal myopathy with rimmed vacuoles (DMRV); Nonaka distal myopathy; and quadriceps-sparing myopathy.
GNE myopathy is a very rare disease which causes weakness and the wasting of muscles in the legs and the arms, and affects approximately 1 person in 1 million people world-wide.
What causes GNE myopathy?
GNE myopathy is an autosomal recessive disease where both parents are usually unaffected (carriers) but can pass on a mutated copy of the GNE gene to their affected child. These mutations prevent the GNE enzyme from functioning correctly, which can have knock-on affects on other muscle proteins and processes (for example a process called sialylation, which is needed for some proteins to function), which are thought to lead to muscle weakness and dysfunction.
What are the signs and symptoms of GNE myopathy?
The onset of symptoms usually first occurs in young adults (usually in the third decade of life), but an earlier or later onset has also been observed in a small number of patients. Initially, increased tripping and a steppage gait are often noted because of foot drop. The condition gets worse slowly and leads to weakness in proximal leg muscles resulting in difficulty climbing stairs or getting up from sitting, and weakness of the hands and shoulder muscles.
How does the disease progress?
The severity of disease progression differs from person to person; however, the disease often leads to disability and the loss of the ability to walk in later life.