Ordering Recommendation

Confirm a clinical diagnosis of familial transthyretin (TTR) amyloidosis, familial euthyroid hyperthyroxinemia, or senile systemic amyloidosis.

Mnemonic
TTR FGS
Methodology

Polymerase Chain Reaction/Sequencing

Performed

Sun-Sat

Reported

Within 14 days

New York DOH Approval Status
Specimens from New York clients will be sent out to a New York DOH approved laboratory, if possible.
Specimen Required
Patient Preparation
Collect

Lavender (EDTA), Pink (K2 EDTA).

Specimen Preparation

Transport 3 mL whole blood. (Min: 1 mL)

Storage/Transport Temperature

Refrigerated.

Unacceptable Conditions
Remarks
Stability

Ambient: 72 hours; Refrigerated: 1 week; Frozen: Unacceptable

Reference Interval
Interpretive Data

Interpretive Data: Background Information for Familial Transthyretin Amyloidosis (TTR) Sequencing:
Characteristics
: Familial Transthyretin Amyloidosis  is caused by pathogenic variants of the TTR gene resulting in abnormal amyloid accumulation in various tissues and is generally categorized into three phenotypes:  1) familial amyloid polyneuropathy, a slowly progressive sensorimotor and autonomic neuropathy; 2) familial amyloid cardiomyopathy, a restrictive cardiomyopathy with cardiomegaly, conduction block, angina, congestive heart failure and aortic dissection/dilatation; and 3) leptomeningeal amyloidosis, primarily affecting the CNS, causing dementia, visual impairment, seizures, ataxia, psychosis, hemorrhage, and hydrocephalus. TTR variants can also be associated with benign familial euthyroid hyperthyroxinemia.
Incidence: 1 in 568 individuals from Northern Portugal; 1 in 100,000 individuals of Northern European ancestry.
Inheritance: Autosomal dominant.
Penetrance: Incomplete.
Cause: Pathogenic TTR gene variants.
Clinical Sensitivity: 99 percent for Familial TTR Amyloidosis.
Methodology: Bidirectional sequencing of all coding regions and intron-exon boundaries of the TTR gene.
Analytical Sensitivity and Specificity: 99 percent.
Limitations: Diagnostic errors can occur due to rare sequence variations. Regulatory region variants, deep intronic variants and large deletions/duplications in TTR will not be detected.

Compliance Category

Laboratory Developed Test (LDT)

Note
Hotline History
N/A
CPT Codes

81404

Components
Component Test Code* Component Chart Name LOINC
2014036 TTR FGS Spec 31208-2
2014037 TTR FGS Interpretation 48033-5
* Component test codes cannot be used to order tests. The information provided here is not sufficient for interface builds; for a complete test mix, please click the sidebar link to access the Interface Map.
Aliases
  • Amyloidosis
  • Polyneuropathy
Familial Transthyretin Amyloidosis (TTR) Sequencing