Myasthenia+Gravis+Genes

MUSK Gene

The gene which appeared most frequently during research was that of muscle-specific tyrosine kinase receptor (MuSK). This is found to help cluster AChR in the neuromuscular junction, allowing the muscle synapse to occur. MuSK proteins have been found to continue the on-going maintenance within the NMJ (Vincent, Angela et al., 2012). Mutations or deletions of this gene play a role in MG since there are multiple areas where the proteins do their work. It has been observed that mutated MuSK antibodies have a negative effect on limb muscles within the transfer in the NMJ (Vincent, Angela et al., 2012), indicating the gene is linked to some roles of skeletal muscles.

The MuSK gene is found on chromosome 9 location 9q31.3q31, indicated by the red line on the figure below ([] under Public Domain accessed Oct 2013).



If the MuSK genes or proteins get blocked or reduced and cannot be signaled, the synaptic membrane becomes impaired (Pal, Jozsef et al., 2011). MuSK genes have not been found within the post-synaptic folds, such as the main location for AChR.

Myasthenia gravis patients get classified as either AChR-MG or MuSK-MG. This is due to noted differences in symptoms with the presence of either AChR or MuSK antibodies. Those to have MuSK-MG have a non-specific muscle atrophy. This means the disease can attack any skeletal muscled area. These patients have an earlier onset, around age 35, but neonatal onset is very rare (Pal, Jozsef et al., 2011). The bulbar form, which attacks the muscles within the medulla oblongata, are more popular. MuSK-MG patients are more prone to myasthenic crisis. This often fatal development of MG patients is a severe weakening of the respiratory muscles (Pal, Jozsef et al., 2011). Also, MuSK-MG patients have no thymic pathology (Pal, Jozsef et al., 2011). The thymus is responsible for maturing and selecting T cells for control over the autoimmune regulation and response. AChR-MG patients have found up to 60 percent have changes within their thymus gland (Pal, Jozsef et al., 2011).

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