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Test ID: BIOTS Biotinidase, Serum

Reporting Name

Biotinidase, S

Useful For

Preferred test for diagnosing biotinidase deficiency

 

Follow-up testing for certain organic acidurias

Specimen Type

Serum


Specimen Required


Collection Container/Tube:

Preferred: Red top

Acceptable: Serum gel

Submission Container/Tube: Plastic vial

Specimen Volume: 1 mL

Collection Instructions: Spin down and immediately remove serum.


Specimen Minimum Volume

0.2 mL

Specimen Stability Information

Specimen Type Temperature Time
Serum Frozen (preferred) 21 days
  Refrigerated  5 days

Reference Values

3.5-13.8 U/L

Day(s) and Time(s) Performed

Monday, Thursday; set up at 8 a.m.

Test Classification

This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the U.S. Food and Drug Administration.

CPT Code Information

82261

LOINC Code Information

Test ID Test Order Name Order LOINC Value
BIOTS Biotinidase, S In Process

 

Result ID Test Result Name Result LOINC Value
50666 Specimen 31208-2
50667 Specimen ID 57723-9
50668 Source 31208-2
50669 Order Date 82785-7
50670 Reason For Referral 42349-1
50671 Method 49549-9
50672 Biotinidase, S 1982-8
50673 Interpretation 59462-2
50674 Amendment In Process
50675 Reviewed By No LOINC Needed
50676 Release Date 82772-5

Clinical Information

Biotinidase deficiency is an autosomal recessive disorder caused by mutations in the biotinidase gene (BTD). Age of onset and clinical phenotype vary among individuals depending on the amount of residual biotinidase activity. Profound biotinidase deficiency occurs in approximately 1 in 137,000 live births and partial biotinidase deficiency occurs in approximately 1 in 110,000 live births, resulting in a combined incidence of about 1 in 61,000. The carrier frequency for biotinidase deficiency within the general population is about 1 in 120.

 

Untreated profound biotinidase deficiency typically manifests within the first decade of life as seizures, ataxia, developmental delay, hypotonia, sensorineural hearing loss, vision problems, skin rash, and alopecia. Partial biotinidase deficiency is associated with a milder clinical presentation, which may include cutaneous symptoms without neurologic involvement. Certain organic acidurias, such as holocarboxylase synthase deficiency, isolated carboxylase synthase deficiency, and 3-methylcrotonylglycinuria, present similarly to biotinidase deficiency. Serum biotinidase levels can help rule out these disorders.

 

Treatment with biotin is successful in preventing the clinical features associated with biotinidase deficiency. In symptomatic patients, treatment will reverse many of the clinical features except developmental delay, vision, and hearing complications. As a result, biotinidase deficiency is included in most newborn screening programs. This enables early identification and treatment of presymptomatic patients.

 

Molecular tests form the basis of confirmatory or carrier testing. When biotinidase enzyme activity is deficient, sequencing of the entire BTD gene (BTDZ / Biotinidase Deficiency, BTD Full Gene Analysis) allows for detection of disease-causing mutations in affected patients. Identification of familial mutations allows for testing of at-risk family members (FMTT / Familial Mutation, Targeted Testing).

 

While genotype-phenotype correlations are not well established, it appears that certain mutations are associated with profound biotinidase deficiency, while others are associated with partial deficiency.

Interpretation

The reference range is 3.5 U/L to 13.8 U/L.

 

Partial deficiencies and carriers may occur at the low end of the reference range.

 

Values less than 3.5 U/L are occasionally seen in specimens from unaffected patients.

Clinical Reference

1. Zempleni J, Barshop BA, Cordonier EL, et al: Disorders of Biotin Metabolism. In The online Metabolic and Molecular Base of Inherited Disease. Edited by D Valle, AL Beaudet, B Vogelstein, et al: New York, McGraw-Hill; 2014. Accessed August 24, 2015. Available at: http://ommbid.mhmedical.com/content.aspx?bookid=971&Sectionid=62646613

2. Wolf B: Biotinidase Deficiency. In GeneReviews. Edited by RA Pagon, MP Adam, HH Ardinger, et al: University of Washington, Seattle, 1993-2016. Updated 2013 Dec 5. Available at: www.ncbi.nlm.nih.gov/books/NBK1322/

Analytic Time

4 days

Method Name

Colorimetric

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.

Mayo Medical Laboratories | Genetics and Pharmacogenomics Catalog Additional Information:

mml-biochemical