congenital myasthenic syndrome 2A

A congenital myasthenic syndrome characterized by autosomal dominant inheritance of postsynaptic neuromuscular junction defects, early-onset progressive muscle weakness, and prolonged opening and activity of the acetylcholine receptor channel that has_material

A congenital myasthenic syndrome characterized by autosomal dominant inheritance of postsynaptic neuromuscular junction defects, early-onset progressive muscle weakness, and prolonged opening and activity of the acetylcholine receptor channel that has_material_basis_in heterozygous mutation in the CHRNB1 gene on chromosome 17p13.

Signs and symptoms

• Poor head control
• Muscle fiber splitting
• Flexion contracture
• Fatigable weakness
• Limb muscle weakness
• High palate
• Delayed ability to sit
• Type 1 muscle fiber predominance
• Abnormally high-pitched voice
• EMG: decremental response of compound muscle action potential to repetitive nerve stimulation

Also known as: CMS2A; congenital myasthenic syndrome 2A slow-channel