Autosomal dominant distal hereditary motor neuronopathy-7 (HMND7) is a neurologic disorder characterized by onset in the second decade of progressive distal muscle wasting and weakness affecting the upper and lower limbs and resulting in walking difficulties and hand grip. There is significant muscle atrophy of the hands and lower limbs. The disorder is associated with vocal cord paresis due to involvement of the tenth cranial nerve (summary by Barwick et al., 2012). For a general phenotypic description and a discussion of genetic heterogeneity of autosomal dominant distal HMN, see HMND1 (182960).

Congenital myasthenic syndrome-13 (CMS13) is an autosomal recessive neuromuscular disorder characterized by onset of proximal muscle weakness in the first decade. EMG classically shows a decremental response to repeated nerve stimulation. Affected individuals show a favorable response to acetylcholinesterase (AChE) inhibitors (summary by Belaya et al., 2012). For a discussion of genetic heterogeneity of CMS, see CMS1A (601462).

Congenital myasthenic syndrome-15 is one of a heterogeneous group of disorders that arise from impaired signal transmission at the neuromuscular synapse and are characterized by fatigable muscle weakness (summary by Cossins et al., 2013). For a discussion of genetic heterogeneity of CMS, see CMS1A (601462).

Congenital myasthenic syndrome-19 (CMS19) is an autosomal recessive disorder resulting from a defect in the neuromuscular junction, causing generalized muscle weakness, exercise intolerance, and respiratory insufficiency. Patients present with hypotonia, feeding difficulties, and respiratory problems soon after birth, but the severity of the weakness and disease course is variable (summary by Logan et al., 2015). For a discussion of genetic heterogeneity of CMS, see CMS1A (601462).