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Nemaline Myopathy
ACTA1 (Skeletal muscle alpha-actin)
Nemaline myopathy is a rare neuromuscular disorder with variable age of onset and clinical severity, ranging from neonatal muscle weakness and hypotonia to childhood or adult skeletal myopathy. The hallmark disease pathology is rod-shaped structures seen in skeletal muscle. Nemaline myopathy is caused by mutation in the ACTA1 gene. It is usually inherited in an autosomal dominant manner (NEM1), with frequent cases resulting from dominant-acting new germline mutations. Children of an affected parent have a 50% chance of inheriting the disease-causing mutation. Nemaline myopathy also can be inherited in an autosomal recessive manner (NEM2). Approximately 15-30% of patients with nemaline myopathy have mutations in the ACTA1 gene. Sequence analysis through GeneDx identifies mutations in nearly all NEM1 and NEM2 patients with ACTA1 mutations. Diagnostic testing includes performing bi-directional sequence analysis of exons 2-7 and the flanking intronic regions. Buccal brushes CANNOT be accepted for this test. Please send 1-5 mL whole blood in EDTA (purple top tube). Carrier testing and prenatal diagnosis are available once mutation in the family has been identified.
Information Sheet for ACTA1 gene testing
Consent Document for ACTA1 gene testing
Nemaline Myopathy (autosomal recessive)
NEB (nebulin)
Using genomic DNA obtained from buccal (cheek) swabs or blood in EDTA, the sample is evaluated for the recurrent deletion mutation which includes exon 55, and surrounding intron sequence, of the NEB gene. This deletion mutation has been observed in 5 of 5 individuals with nemaline myopathy and Ashkenazi Jewish ancestry (Anderson et al. Nemaline myopathy in the Ashkenazi Jewish population is caused by a deletion in the nebulin gene. Hum Genet 115:185-190, 2004). In additional to diagnostic testing in affected individuals, testing to determine carrier status for this deletion is available (e.g. for the partner of a carrier, relatives of an affected individual, other persons of Ashkenazi Jewish ancestry). Prenatal diagnosis is available for those couples determined to be at risk of producing an affected child.
Information Sheet for Nebulin gene testing
Consent Document for Nebulin gene testing
Genetic Test Sample Submission Form (Test Requisition Form) including Payment Options
nemaline myopathy, actin, acta1, nebulin, myopathy, nemaline rod, tropomyosin, muscular dystrophy
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