Test Catalog

Test ID: PLAFL    
Platelet Surface Glycoprotein by Flow Cytometry, Blood

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

Identification of markedly decreased CD41 (GPIIb) and CD61 (GPIIIa) expression levels, which are diagnostic for Glanzmann thrombasthenia

 

Identification of markedly decreased CD42a (GPIX) and CD42b (GPIb-alpha) expression levels, which are diagnostic for Bernard-Soulier syndrome

 

Identification of decreased GPVI expression, which suggests collagen receptor deficiency

 

Identification of decreased CD49b (GPIa), which suggests collagen receptor deficiency

Genetics Test Information Provides information that may help with selection of the correct genetic test or proper submission of the test request

 

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

Platelets have essential roles in primary hemostasis. Exposed collagen at a vascular damage site can activate platelets via collagen receptor GPVI and GPIa and bind shear-stretched multimeric VWF proteins, which subsequently interact with the platelet surface receptor, GPIb-V-IX. Upon full activation, platelets can aggregate by binding to fibrinogen through activated GPIIb-GPIIIa receptors. Deficiency of platelet surface glycoproteins can cause bleeding diathesis.

 

Platelet flow cytometric analysis is the preferred method to assess hereditary platelet disorders due to quantitative surface glycoprotein (GP) deficiencies. GP expression levels can be measured by using fluorescent-conjugated GP-specific antibodies and their fluorescent intensities can be compared to normal ranges of various glycoproteins.

 

CD Number

Glycoprotein Name

Integrin Name

CD41

GPIIb

Alpha 2b

CD42a

GPIX

NA

CD42b

GPIb-alpha

NA

CD49b

GPIa

Alpha 2

CD61

GPIIIa

Beta 3

NA

GPVI

NA

Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.

GPIIb CD41: > or =70.0% (Normal Range-Median)

GPIIIa CD61: > or =70.0% (Normal Range-Median)

GPIX CD42a: > or =70.0% (Normal Range-Median)

GPIb-alpha CD42b: > or =70.0% (Normal Range-Median)

GPIa CD49b: > or =60.0% (Normal Range-Median)

Interpretation Provides information to assist in interpretation of the test results

CD Markers

% Reference Range Median

Comments

CD41 and CD61

50%-69%

(Marginally)

Marginally decreased platelet surface receptors CD41 (GPIIb) and CD61 (GPIIIa) are of uncertain clinical significance. This finding could be a laboratory artifact due to suboptimal sample condition, benign polymorphisms, or a heterozygous state of Glanzmann thrombasthenia. Recommend correlation with patient's clinical findings and results of platelet functional studies, and consider repeating platelet glycoprotein profile studies by flow cytometry to verify the present finding if clinically indicated.

30%-50%: (Moderately)

 

<30%: (Markedly)

Platelet surface expression of CD41 (GPIIb) and CD61 (GPIIIa) are moderately or markedly decreased. This finding is suggestive for a variant of Glanzmann thrombasthenia. Recommend correlation with patient's clinical findings and results of platelet functional studies, and consider repeating platelet glycoprotein profile studies by flow cytometry to verify the present finding if clinically indicated.

CD42a and CD42b

 

 

50%-69%

(Marginally)

Marginally decreased platelet surface receptors CD42a (GPIX) and CD42b (GPIb-alpha) are of uncertain clinical significance. This finding could be a laboratory artifact due to suboptimal sample condition, benign polymorphisms, or a heterozygous state of Bernard-Soulier syndrome. Recommend correlation with patient's clinical findings and results of platelet functional studies, and consider repeating platelet glycoprotein profile studies by flow cytometry to verify the present finding if clinically indicated.

30%-50%: (Moderately)

 

<30%: (Markedly)

Platelet surface expression of CD42a (GPIX) and CD42b (GPIb-alpha) are moderately or markedly decreased. This finding is suggestive for a variant of Bernard-Soulier syndrome. Recommend correlation with patient's clinical findings and results of platelet functional studies, and consider repeating platelet glycoprotein profile studies by flow cytometry to verify the present finding if clinically indicated.

CD49b

30%-59%

(Marginally)

Marginally decreased platelet surface receptor CD49b (GPIa) is of uncertain clinical significance. This finding could be a laboratory artifact due to suboptimal sample condition, a benign polymorphism, or a variant of platelet collagen receptor glycoprotein Ia/IIa deficiency. Recommend correlation with patient's clinical findings and results of platelet functional studies, and consider repeating platelet glycoprotein profile studies by flow cytometry to verify the present finding if clinically indicated.

10%-30% (moderately)

 

<10%

(Markedly)

Platelet surface expression of CD49b (GPIa) is moderately or markedly decreased. This finding is suggestive for a variant of a variant of platelet collagen receptor glycoprotein Ia/IIa deficiency. Recommend correlation with patient's clinical findings and results of platelet functional studies, and consider repeating platelet glycoprotein profile studies by flow cytometry to verify the present finding if clinically indicated.

GPVI

50%-69%

(Marginally)

Marginally decreased platelet surface receptor glycoprotein VI (GPVI) is of uncertain clinical significance. This finding could be a laboratory artifact due to suboptimal sample condition, a benign polymorphism or a variant of platelet collagen receptor GPVI deficiency. Recommend correlation with patient's clinical findings and results of platelet functional studies, and consider repeating platelet glycoprotein profile studies by flow cytometry to verify the present finding if clinically indicated.

30%-50% (moderately)

 

<30%

(Markedly)

Platelet surface expression of glycoprotein VI (GPVI) is moderately or markedly decreased. This finding is suggestive for a variant of a variant of platelet collagen receptor GPVI deficiency. Recommend correlation with patient's clinical findings and results of platelet functional studies, and consider repeating platelet glycoprotein profile studies by flow cytometry to verify the present finding if clinically indicated.

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

Suboptimal sample condition due to improper blood draw, transportation or storage may cause fluctuation of platelet surface receptors and consequently influence the results of platelet surface receptor measurement by flow cytometry.

Supportive Data

Platelet glycoprotein flow cytometry method was established in the Mayo special coagulation laboratory in 2009. Between the years of 2009 to 2014, a total of 155 clinical patients were tested. The flow cytometry results were compared with the final impressions of platelet light transmission aggregation testing. There were 7 samples that had flow cytometric features of Glanzmann thrombasthenia, 2 samples that had flow cytometric features of Bernard-Soulier syndrome, and 3 samples that had flow cytometric features of May-Hegglin anomaly. All flow cytometric results were concordant with platelet light transmission aggregation results and other clinical findings.

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

1. Miller, JL: Glycoprotein analysis for the diagnostic evaluation of platelet disorders. Semin Thromb Hemost 2009;35(2):224-232

2. Kannan M, Ahmad F, Yadav BK, et al: Carrier detection in Glanzmann thrombasthenia: comparison of flow cytometry and Western blot with respect to DNA mutation. Am J Clin Pathol 2008;130(1):93-98

3. Savoia A, Pastore A, De Rocco D, et al: Clinical and genetic aspects of Bernard-Soulier syndrome: searching for genotype/phenotype correlations. Haematologica 2011;96(3):417-423

4. Nurden AT, Freson K, Selifsohn U: Inherited platelet disorders. Haemophilia 2012;18(4):154-160

5. Dumont B, Lasne D, Rothschild C, et al: Absence of collagen-induced platelet activation caused by compound heterozygous GPVI mutations. Blood 2009;114(9):1900-1903

Special Instructions Library of PDFs including pertinent information and forms related to the test