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Epic Test Code LGBBS Globotriaosylsphingosine, Blood Spot


Specimen Required


Supplies: Card-Blood Spot Collection (Filter Paper) (T493), Card-Postmortem Screening (Filter Paper) (T525)

Container/Tube:

Preferred: Blood Spot Collection (Filter Paper) (T493)

Acceptable: Ahlstrom 226 filter paper, Munktell filter paper, or Postmortem Screening Card (T525)

Specimen Volume: 2 blood spots

Collection Instructions:

1. Let blood dry on filter paper at room temperature in a horizontal position for 3 or more hours.

2. At least 1 spot should be complete, (ie, unpunched).

3. Do not expose specimen to heat or direct sunlight.

4. Do not stack wet specimens.

5. Keep specimen dry.

6. Dried blood spots collected with EDTA, sodium heparin, lithium heparin, or ACD B-containing devices are acceptable.

Additional Information:

1. For collection instructions in Spanish, see Blood Spot Collection Card-Spanish Instructions (T777) in Special Instructions.

2. For collection instructions in Chinese, see Blood Spot Collection Card-Chinese Instructions (T800) in Special Instructions.


Forms

New York Clients-Informed consent is required. Please document on the request form or electronic order that a copy is on file. An Informed Consent for Genetic Testing (T576) is available in Special Instructions.

Useful For

Diagnosing and monitoring of patients with Fabry disease

Method Name

Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS)

Reporting Name

Globotriaosylsphingosine, BS

Specimen Type

Whole blood

Specimen Minimum Volume

0.25 mL

Specimen Stability Information

Specimen Type Temperature Time
Whole blood Refrigerated (preferred) 10 days
  Frozen  59 days
  Ambient  10 days

Reject Due To

Hemolysis

NA

Lipemia

NA

Icterus

NA

Other

Blood spot specimen that shows serum rings, insufficient specimen

Clinical Information

Fabry disease is an X-linked recessive lysosomal storage disorder caused by a deficiency of the enzyme alpha-galactosidase A (alpha-Gal A). Reduced enzyme activity results in accumulation of glycosphingolipids in the lysosomes throughout the body, in particular, the kidney, heart, and brain. Severity and onset of symptoms are dependent on the residual enzyme activity. Symptoms may include acroparesthesias (pain crises), multiple angiokeratomas, reduced or absent sweating, corneal opacity, renal insufficiency leading to end-stage renal disease, and cardiac and cerebrovascular disease. There are renal and cardiac variant forms of Fabry disease that may be underdiagnosed. Heterozygous females of Fabry disease can have clinical presentations ranging from asymptomatic to severely affected, and they may have alpha-Gal A activity in the normal range. The estimated incidence varies from 1 in 3,000 infants detected via newborn screening to 1 in 10,000 males diagnosed after onset of symptoms.

 

Unless irreversible damage has already occurred, treatment with enzyme replacement therapy (ERT) has led to significant clinical improvement in affected individuals. For this reason, early diagnosis and treatment are desirable, and early detection of Fabry disease through newborn screening has been implemented in a few US states.

 

Absent or reduced alpha-Gal A in blood spots, leukocytes (AGA / Alpha-Galactosidase, Leukocytes), serum (AGAS / Alpha-Galactosidase, Serum), or blood spot (AGABS / Alpha-Galactosidase, Blood Spot) can indicate a diagnosis of classic or variant Fabry disease. Molecular sequence analysis of the GLA gene (FABRZ / Fabry Disease, Full Gene Analysis) allows for detection of the disease-causing mutation in males and females. Molecular genetic testing is the recommended diagnostic test for females as alpha-galactosidase activity may be in the normal range in an affected female patient.

The glycosphingolipid, globotriaosylsphingosine (LGb3), may be elevated in symptomatic patients and supports a diagnosis of Fabry disease. It may also be helpful as a tool for monitoring disease progression as well as determining treatment response in known patients. In addition, measurement or globotriaosylsphingosine (LGb3), may provide additional diagnostic information in the evaluation of uncertain cases, such as in asymptomatic heterozygous females, individuals with novel GLA variants of unclear clinical significance, as well as asymptomatic patients identified by family screening.

Reference Values

GLOBOTRIAOSYLSPHINGOSINE (LGb3)

Cutoff: ≤0.034 nmol/mL

Interpretation

An elevation of globotriaosylsphingosine (LGb3) is suggestive of Fabry disease.

Cautions

Some patients with Fabry disease may have normal concentrations of globotriaosylsphingosine (LGb3).

Day(s) and Time(s) Performed

Tuesday and Thursday 8 a.m.

Analytic Time

2 days (not reported on Saturday or Sunday)

Specimen Retention Time

Normal: 1 year; Abnormal: Indefinitely

Performing Laboratory

Mayo Clinic Laboratories in Rochester

CPT Code Information

82542

NY State Approved

Yes