CYTOCHROME b (MTCYB)

DESCRIPTION - Mitochondrial DNA Analysis

Mutations of the mitochondrially encoded human cytochrome b gene (MTCYB) are almost exclusively associated with isolated complex III deficiency in muscle. Cytochrome b is essential for assembly and function of complex III. Cytochrome b is the only protein subunit of complex III (ubiquinol-cytochrome c oxidoreductase). Complex III is a hydrophobic integral membrane protein with eight transmembrane helices and contains 11 polypeptides. In many patients the mutation appears to arise sporadically and is restricted to muscle tissue. This most often affects young adults who display skeletal muscle weakness and exercise intolerance, and may also exhibit myoglobinuria and mitochondrial proliferation as evidenced by the presence of ragged-red fibers (RRF) on muscle biopsy. Children with cytochrome b mutations have been reported and display mitochondrial encephalopathy, cardiomyopathy, septo-optic dysplasia, and multisystem disorders.

Test Order Code MTDNA-CYTB

CPT Codes

83891 x 1, 83898 x 4, 83904 x 8

 

Indications For Testing

  • Confirm diagnosis of affected individuals with;

  • Family history of mitochondrial disorders

  • Matrilineal family members with known mitochondrial DNA mutations and asymptomatic carrier testing

  • Confirmation of mitochondrial mutations

Turn Around Time

 Less than two weeks. Expedited analysis is available upon request for an additional charge.
Specimen Requirements

Ship one of the following:

Peripheral Blood
Peripheral blood collection requires a Lavender-top (EDTA) vaccutainer tube available in the DNA Specimen Collection Kit. Keep sample at ambient temperature and ship by overnight courier to arrive at the Molecular Laboratory within 24 hrs after collection of the specimen. If shipment is delayed by one or two days, the specimen should be refrigerated and shipped at room temperature.

  • Adults: 1 tube with 7.0 mL whole blood

  • Children & Infants: 1 tube with 5-6 mL whole blood

Muscle Biopsy
Tissue can be fresh or frozen, and must be shipped on dry ice.

  • Adults: 40-50 mg

  • Children: 25 mg

Specimen Kits DNA Specimen Collection Kits can be obtained from Transgenomic Molecular Laboratory.
Shipping and Contact Information Transgenomic Molecular Laboratory
12325 Emmet Street Omaha, NE 68164 USA
Phone: (866) 500-GENE / (866) 500-4363 Fax: (402) 452-5447
E-mail: labservice@transgenomiclabs.com
Test Submission  and Patient Consent Forms

Due to the unique nature of genetic testing, patients should receive pre-test and post-test counseling. Informed consent is recommended.

Test Methodology Genomic DNA is amplified by PCR for the specification region of interest and sequenced for confirmation.

Additional References

Mitomap
A human mitochondrial genome database.  http://www.mitomap.org/

Note: The performance characteristics of this test were validated by TRANSGENOMIC Molecular Laboratory. The U.S. Food and Drug Administration (FDA) has not approved this test. However, FDA approval is currently not required for clinical use of this test. The results are not intended to be used as the sole means for clinical diagnosis or patient management decisions. TRANSGENOMIC Molecular Laboratory is authorized under Clinical Laboratory Improvement Amendments (CLIA) to perform high-complexity testing.

TRANSGENOMIC MOLECULAR LABORATORY

Phone: (866) 500-GENE/ (866) 500-4363

FAX: (402) 452-5447