Pathology Handbook

Common Mitochondrial Mutation/DNA Depletion studies

Specimen Requirements

EDTA blood: Adult: 1 x 4 ml, Child: 1-2 ml

Prenatal: Amniotic Fluid 20ml; Chorionic Villus 20mg

Urine: 10-20ml (preferably early morning)

Liver/Muscle: 1-5mg tissue samples must be stored at -70°C (-20°C is inadequate) until transport on dry ice. Once frozen, they must not be allowed to thaw.

Mutation Panel: Ideal sample type is blood and urine for MELAS testing.
Deletion Screening: Ideal sample type is muscle in adults and blood in children.
Depletion Testing: Ideal sample type is Liver/Muscle.
Some heteroplasmic mtDNA mutations disappear from blood with age. Therefore if tissue biopsies are available, these may be more suitable than blood for mtDNA analysis.

Reporting time

4 - 6 weeks (mutation panel)

6 - 8 weeks (Deletion, Duplication, Depletion)

1 - 3 weeks (prenatal)

Notes:

Patient to be referred to a genetics clinic for prenatal testing.

Overview

Disorders of mitochondrial energy generation can be caused by primary mutations in mitochondrial DNA (point mutations and single deletions) and secondary mutations in mitochondrial DNA (multiple deletions or depletion of mitochondrial DNA) caused by nuclear gene disorders. The range of testing offered by VCGS includes a panel of 22 of the most common mitochondrial DNA point mutations and tests for mitochondrial DNA deletions and depletion. A significant consideration with testing for mitochondrial DNA mutations is that some mutations can be absent from samples such as blood and saliva. For example, urine sediment is preferred as a sample for adults suspected of MELAS, while muscle or liver biopsies may be the most appropriate sample for testing mitochondrial DNA deletions or depletion.

Contacts:

Phone: 1300 11 8247
Email: vcgs@vcgs.org.au