Congenital myasthenic syndromes (CMS) are neuromuscular hereditary diseases with the symptoms of fatigue, weakness, ptosis, ophthalmoparesis and respiratory problems. This disease group is classified as CMS originating from the presynaptic region, synaptic gap and postsynaptic region according to the origin of the neuromuscular junction. Most of these patients are affected by receptor defects originating from the postsynaptic gap. Here, we present a case who was thirteen years old and had a CHRNE genotype p.Y124 *(c.372C> G) homozygous mutation, which is associated with weakness, low voice, ophthalmoparesis and frequent respiratory infection since birth. Our patient has been diagnosed with non-kinetic AChR deficiency and the case is important with the detection of a new mutation.