OMIM ID:
Nemaline Myopathy 10
Alternate Names
Defective Genes
Clinical Characteristics
Ocular Features
Ophthalmoplegia has been reported in 29% of patients.
Systemic Features
In this form of nemaline myopathy, polyhydramnios, weak or absent fetal movements, and joint contractures may be noted during the antenatal period. Hypotonia and generalized weakness, respiratory difficulties, feeding difficulties and evidence of bulbar weakness may be noted at birth. Many patients die of respiratory failure in the neonatal period but some may survive into the second decade.
Cardiac function is normal.
Genetics
Inheritance
This autosomal recessive disorder results from homozygous or compound heterozygous mutations in the LMOD3 gene (3p14.1). This gene is expressed in both skeletal and cardiac muscle and its product is essential for the organization of sarcomeric thin filaments in skeletal muscle.
Mutations in at least 10 genes cause nemaline myopathy.
Pedigree
Autosomal recessive
In order for autosomal recessive disorders to be expressed, offspring generally must inherit two mutations, one from each carrier parent. Carriers with only one mutation, such as the parents, do not have clinical disease. Note that carrier parents can expect that 1 in 4 children (25%) will inherit both mutations and have the disorder, 2 in 4 children (50%) will be carriers like their parents, while 1 in 4 children (25%) inherit neither mutation.
In order for autosomal recessive disorders to be expressed, offspring generally must inherit two mutations, one from each carrier parent. Carriers with only one mutation, such as the parents, do not have clinical disease. Note that carrier parents can expect that 1 in 4 children (25%) will inherit both mutations and have the disorder, 2 in 4 children (50%) will be carriers like their parents, while 1 in 4 children (25%) inherit neither mutation.