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Familial Amyloidosis DNA Sequencing
MessagePerforming Lab: Mayo
Test Code
5440
Alias/See Also
Sunquest: AMYDS; Transthyretin (TTR) Gene
CPT Codes
81404
Includes
http://www.mayomedicallaboratories.com/test-catalog/Overview/35352
Print and submit "Molecular Genetics Information Sheet(T521)" available online at Mayo's website at www.mayomedicallaboratories.com, Genetic Testing.
Print and submit "Molecular Genetics Information Sheet(T521)" available online at Mayo's website at www.mayomedicallaboratories.com, Genetic Testing.
Preferred Specimen
3.0 mL EDTA (whole blood)
Minimum Volume
0.5 mL
Other Acceptable Specimens
Pink top or Yellow top, Whole Blood
Instructions
See link in "Includes" section for additional information
Collect 3.0 mL Lavender Top Tube, Whole Blood
Collect 3.0 mL Lavender Top Tube, Whole Blood
Transport Temperature
Room Temperature
Specimen Stability
Specimen preferred within 96 hours of draw
Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)
Specimen not sent in original collection tube.
Methodology
Polymerase Chain Reaction (PCR) Amplification/DNA Sequencing
Setup Schedule
Weekly
Report Available
Results are generally reported between 14 -20 days
Limitations
Shipping: Specimen must arrive within 96 hrs of collection. Must be in Original Tube
Reference Range
An interpretive report will be provided
Clinical Significance
The systemic amyloidoses are a number of disorders of varying etiology characterized by extracellular protein deposition. The most common form is an acquired amyloidosis secondary to multiple myeloma or monoclonal gammopathy of unknown significance (MGUS) in which the amyloid is composed of immunoglobulin light chains. In addition to light chain amyloidosis, there are a number of acquired amyloidoses caused by the misfolding and precipitation of a wide variety of proteins. There are also hereditary forms of amyloidosis. Due to the clinical overlap between the acquired and hereditary forms, it is imperative to determine the specific type of amyloidosis in order to provide an accurate prognosis and consider appropriate therapeutic interventions.
The most common hereditary amyloidosis is familial transthyretin amyloidosis; an autosomal dominant disorder caused by mutations in the transthyretin (TTR) gene. The resulting amino acid substitutions lead to a relatively unstable, amyloidogenic TTR protein. Most individuals begin to exhibit clinical symptoms between the third and seventh decades of life. Typically, TTR-associated amyloidosis is progressive over a course of 5 to 15 years and the most common cause of death is cardiomyopathy. Affected individuals may present with a variety of symptoms, including peripheral neuropathy, blindness, cardiomyopathy, nephropathy, autonomic nervous dysfunction, or bowel dysfunction.
More than 90 mutations have now been identified within the TTR gene which cause TTR-associated familial amyloidosis. Most of the mutations described to date are single base pair changes that result in an amino acid substitution. Some of these mutations correlate with the clinical presentation of amyloidosis. However, several different mutations have been identified which exhibit considerable clinical overlap.
It is important to note that this assay does not detect mutations associated with non-TTR forms of familial amyloidosis. Therefore, it is important to first test an affected family member to determine if TTR is involved and to document a specific mutation in the family before testing at risk individuals.
The most common hereditary amyloidosis is familial transthyretin amyloidosis; an autosomal dominant disorder caused by mutations in the transthyretin (TTR) gene. The resulting amino acid substitutions lead to a relatively unstable, amyloidogenic TTR protein. Most individuals begin to exhibit clinical symptoms between the third and seventh decades of life. Typically, TTR-associated amyloidosis is progressive over a course of 5 to 15 years and the most common cause of death is cardiomyopathy. Affected individuals may present with a variety of symptoms, including peripheral neuropathy, blindness, cardiomyopathy, nephropathy, autonomic nervous dysfunction, or bowel dysfunction.
More than 90 mutations have now been identified within the TTR gene which cause TTR-associated familial amyloidosis. Most of the mutations described to date are single base pair changes that result in an amino acid substitution. Some of these mutations correlate with the clinical presentation of amyloidosis. However, several different mutations have been identified which exhibit considerable clinical overlap.
It is important to note that this assay does not detect mutations associated with non-TTR forms of familial amyloidosis. Therefore, it is important to first test an affected family member to determine if TTR is involved and to document a specific mutation in the family before testing at risk individuals.
