Test Catalog

Test ID: PHTDP    
Phosphorylated TDP43 Immunostain, Technical Component Only

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

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

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

TAR DNA-binding protein 43 (TDP-43) has multiple functions in transcriptional repression, translational regulation, and pre-mRNA splicing. In normal cells, TDP-43 is found in the nucleus, whereas in affected cells TDP-43 is phosphorylated and found in intracytoplasmic inclusions and neurites. The phosphoTDP-43-specific antibody will only stain the intracytoplasmic inclusions and neurites, thus highlighting the patterns that are hallmarks for amyotrophic lateral sclerosis (ALS) and frontotemporal lobular degeneration.

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 within 6 weeks.

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

1. Ling JP, Pletnikova O, Troncoso JC, et al: TDP-43 repression of nonconserved cryptic exons is compromised in ALS-FTD. Science 2015 Aug 7;349(6248):650-655

2. Hasegawa M, Arai T, Nonaka T, et al: Phosphorylated TDP-43 in frontotemporal lobar degeneration and amyotrophic lateral sclerosis. Ann Neurol 2008 Jul;64(1):60-70

3. Lee EB, Lee VM, Trojanowski JQ: Gains or losses: molecular mechanisms of TDP43-mediated neurodegeneration. Nat Rev Neurosci 2011 Nov 30;13(1):38-50

4. Smethurst P, Sidle KCL, Hardy J: Review: Prion-like mechanisms of transactive response DNA binding protein of 43 kDa (TDP-43) in amyotrophic lateral sclerosis (ALS). Neuropathol Appl Neurobiol 2015;41(5):578-597

5. Serrano GE, Intorcia A, Carew J, et al: Feasibility Study: Comparison of Frontal Cortex Needle Core Versus Open Biopsy for Detection of Characteristic Proteinopathies of Neurodegenerative Diseases. J Neuropathol Exp Neurol 2015;74(9):934-942