engleski

Congenital myasthenic syndromes (CMS)

CMS are genetically determined disorders affecting safety margins of neural transmission at presynaptic, postsynaptic and synaptic level. Diagnosis of CMS is made<on clinical symotoms including fatigable muscle weakness since infancy or childhood, decremental EMG response and negative AChR antibodies. In some CMS the oset is delayed, weakness and EMG abnormalities appear intermittently in restricted distribution. Investigations of CMS include light and electronmicroscopy of EP morphology, electrophysiology of EP function, currents and potentials, molecular genetic analysis and expresion studies eith mutant molecule. Presynaptic forms include CMS associated with episodic apnea and decreased ACh resynthesis and vesicular filling, CMS with paucity os synaptic vesicles and CMS with EMG findings resembling to Lambert Eaton syndrome. Presynaptic CMS are associated with recessive CHAT gene mutations. The synaptic form is caused by mutation of collagenic tail subunitof AChE gene. However the most of CMS are postsynaptic, mostly caused by mutations of ACHR subunits. Various mutations of the epsilon AChR subunit gene have been reported in CMS. In general, nonsense or frame shifting mutations cause CMS by decreased or absent protein expression and are inherited in autosomal recessive traits. Rapsyn mutations cause promary endplate AChR deficiency. In contrast, missense mutations of the channel pore lining domains may alter the electrophysiological properties of the channel resulting in the so-called Slow<Channel Congenital Myasthenic Syndrome (SCCMS). SCCMS are usually inherited as autosomal dominant traits.

Congenital myasthenic syndrome

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