Lab Dept:

Anatomic Pathology

Test Name:

MELAS SYNDROME (MTTL1) KNOWN MUTATION

General Information

Lab Order Codes:

MELSK

Synonyms:

Hearing Loss Genes; MTTL1-A3243G Mutation; Diabetes-deafness syndrome

CPT Codes:

83891 – Isolation or extraction of highly purified nucleic acid

83894 – Separation by gel electrophoresis

83898 – Amplification of patient nucleic acid, each nucleic acid sequence

83904 – Mutation identification by sequencing, single segment, each segment

Test Includes:

Carrier testing for MTTL1.

Logistics

Test Indications:

Testing of a relative for a specific known mutation (carrier testing).

MTTL1 encodes the mitochondrial transfer RNA-Leucine protein. The A3243G mutation has been found in several families segregating maternally inherited diabetes mellitus and sensorineural hearing loss. The A3243G mutation also is found in MELAS. In population studies of diabetics, the A3243G mutation is found in a small percent of patients.

Lab Testing Section:

Anatomic Pathology - Sendouts

Referred to:

University of Iowa, Dr. Richard Smith

Phone Numbers:

Minneapolis:

Saint Paul:

612-813-6280

651-220-6550

Test Availability:

Monday – Thursday, 24 hours

Turnaround Time:

3 months

Special Instructions:

Include clinical data, specifically audiograms, CT/MRI reports, and pedigree information. Include name, e-mail, and telephone number of contact person (physician or genetic counselor). Do NOT send on Friday or Saturday.

Specimen

Specimen Type:

Whole blood

Container:

Lavender top (EDTA) tube

Draw Volume:

10.0 mL (Minimum 8.0 mL) blood

Processed Volume:

8.0 – 10.0 mL whole blood

Collection:

Routine venipuncture

Special Processing:

Send lavender tubes labeled with a minimum of Name, Date of Birth, and Age. Include clinical data, specifically audiograms, CT/MRI reports, and pedigree information. Include name, e-mail, and telephone number of contact person (physician or genetic counselor). Mail overnight delivery at Room Temperature Monday - Thursday. Do Not send on Friday or Saturday. Samples may be refrigerated if delivery is delayed.

Patient Preparation:

None

Sample Rejection:

Specimens older than 48 hours

Interpretive

Reference Range:

No abnormal allele variants detected

Methodology:

DHPLC and sequencing

References:

Clinical Diagnostics Service, Molecular Otolaryngology Research Lab information sheet from the University of Iowa.