A type of nemaline myopathy that shows features of typical nemaline myopathy in neonates with a more severe progression. Neonates present with spontaneous anti-gravity movements and active respiratory muscles, but with a progressive generalized weakness which prevents achievement of gross motor milestones or leads to loss of ambulation and/or independent respiration by age 11 years. Children often develop joint contractures. The ACTA1 (1q42.13), NEB (2q22) or TPM3 (1q21.2) genes have been associated with this disease. The transmission pattern of the disease is autosomal recessive or dominant. [from
SNOMEDCT_US]