Test Catalog

Test ID: FUSI    
FUS Immunostain, Technical Component Only

Useful For Suggests clinical disorders or settings where the test may be helpful

Identification of frontotemporal lobar dementia (FTLD)

Testing Algorithm Delineates situations when tests are added to the initial order. This includes reflex and additional tests.

For the initial technical component only immunohistochemical (IHC) stain performed, the appropriate bill-only test ID will be reflexed and charged (IHTOI). For each additional technical component only IHC stain performed, an additional bill-only test ID will be reflexed and charged (IHTOA).

Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

FUS (also known as "translated in liposarcoma" TLS) protein is a multifunctional DNA- and RNA-binding protein. Studies have shown the cause of familial amyotrophic lateral sclerosis (ALS) to be a mutation in the gene encoding the FUS protein. FUS has been linked to other neurodegenerative diseases including frontotemporal lobar dementia (FTLD), and neuronal intermediate filament inclusion disease (NIFID).

Interpretation Provides information to assist in interpretation of the test results

This test includes only technical performance of the stain (no pathologist interpretation is performed). Mayo Clinic cannot provide an interpretation of tech only stains outside the context of a pathology consultation. If an interpretation is needed, refer to PATHC / Pathology Consultation for a full diagnostic evaluation or second opinion of the case. All material associated with the case is required. Additional specific stains may be requested as part of the pathology consultation, and will be performed as necessary at the discretion of the Mayo pathologist.


The positive and negative controls are verified as showing appropriate immunoreactivity and documentation is retained at Mayo Clinic Rochester. If a control tissue is not included on the slide, a scanned image of the relevant quality control tissue is available upon request. Contact 855-516-8404.


Interpretation of this test should be performed in the context of the patient's clinical history and other diagnostic tests by a qualified pathologist.

Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

Age of a cut paraffin section can affect immunoreactivity. Stability thresholds vary widely among published literature and are antigen-dependent. Best practice is for paraffin sections to be cut fresh.

Clinical Reference Recommendations for in-depth reading of a clinical nature

1. Kwiatkowski TJ Jr, Bosco DA, LeClerc AL, et al: Mutations in the FUS/TLS Gene on Chromosome 16 Cause Familial Amyotrophic Lateral Sclerosis. Science, 2009;323:1205-1208

2. Loy CT, McCusker E, Kril JJ, et al: Very Early-Onset Frontotemporal Dementia with no Family History Predicts Underlying Fused In Sarcoma Pathology. Brain 2010;133:1-2

3. Munoz DG, Neumann M, Kusaka H, et al: FUS Pathology in Basophilic Inclusion Body Disease. Acta Neuropathol 2009;118:617-627

4. Neumann M, Bentmann E, Dormann D, et al: FET Proteins TAF15 and EWS are Selective Markers that Distinguish FTLD with FUS Pathology from Amyotrophic Lateral Sclerosis with FUS Mutations. Brain 2011;134:2595-2609

5. Neumann M, Rademakers R, Roeber S, et al: A New Subtype of Frontotemporal Lobar Degeneration with FUS Pathology. Brain 2009;132:2922-2931

6. Neumann M, Roeber S, Kretzchmar HA, et al: Abundant FUS-Immunoreactive Pathology in Neuronal Intermediate Filament Inclusion Disease. Acta Neuropathol 2009;118:605-616

7. Urwin H, Josephs KA, Rohrer JD, et al: FUS Pathology Defines the Majority of Tau- and TDP-43- Negative Frontotemporal Lobar Degeneration. Acta Neuropathol 2010;120:33-41