Gene: EMD
Protein: emerin
Clinical characteristics:
- Joint contractures beginning in early childhood - especially of elbows, ankles, and neck
- Slowly progressive muscle weakness, beginning in upper arms and lower legs, and progressing to shoulders and hips
- Cardiac disease with conduction defects and arrhythmias
- Female carriers are at risk for cardiac disease
Inheritance pattern: X-linked; carrier females may be affected with cardiac disease
What this test can tell us:
Testing is performed by sequencing the entire coding region of EMD. This will detect point mutations, small deletions, and small insertions. For females, the assay will not detect a partial or whole gene deletion. For males, a partial or whole gene deletion may appear as failure to amplify a region of the gene.
This assay will detect mutations in EMD in greater than 99% of individuals with a clear pattern of X-linked inheritance and/or with no emerin detected by immunodetection methods.
A negative test result does not rule out a diagnosis of Emery-Dreifuss muscular dystrophy (EDMD). X-linked EDMD can be caused by mutations in either EMD or FHL1. Autosomal dominant and autosomal recessive forms of EDMD can be caused by mutations in LMNA.
A negative test does not rule out a genetic cause of muscular dystrophy. There are many other genes associated with different types of muscular dystrophy, some of which have features in common with EDMD.
Sample requirements: Draw one or two 4-cc tubes of blood in EDTA/purple-top tube (minimum of 1-2 cc for infants).
Turn-around time: Two weeks
CPT codes and cost: 83891 (x1) 83898 (x4) 83904 (x10) 83912 (x1)
Proband: $ 450
Carrier: $ 240