NCT03216252

DNA QUANTIFICATION TECHNIQUE AS A INTERPRETATION TOOL IN MITOCHONDRIAL DISEASES

Completed NA Last updated 15 November 2023

What this trial tests

NA trial testing samples in Mitochondrial Diseases in 10 participants. Completed in 30 September 2020.

Timeline

2 February 2018

Primary endpoint
30 September 2020

30 September 2020

Quick facts

Lead sponsor	Centre Hospitalier Universitaire de Nice
Phase	NA
Status	Completed
Study type	INTERVENTIONAL
Allocation	na
Design	single group
Masking	none
Primary purpose	basic science
Enrollment	10
Start date	2 February 2018
Primary completion	30 September 2020
Estimated completion	30 September 2020
Sites	1 location across France

Drugs / interventions tested

• samples — full drug profile →

Conditions studied

• Mitochondrial Diseases — all drugs for Mitochondrial Diseases →

Sponsor

Centre Hospitalier Universitaire de Nice

Who can join

0 and older, any sex, with Mitochondrial Diseases. Patients with the condition only — healthy volunteers not accepted.

Sponsor's own description

2622/5000 Mitochondrial diseases (MM) are the most common metabolic diseases. Since these pathologies are very heterogeneous in clinical terms, only the identification of mutations in nuclear genes or mitochondrial DNA confirms the diagnosis.

The full-scale study of mtDNA by high-throughput sequencing (NGS) is a first step in the diagnostic approach. The recent introduction of this revolutionary new technology has greatly increased the efficiency of mutation identification. However, in addition to known pathogenic mutations, NGS reveals numerous variants whose significance is currently unknown. A major challenge to obtain a reliable diagnosis is therefore the interpretation of the clinical impact of these new rare variants which proves to be very difficult.

Pathogenicity criteria allow the classification of variants from benign to pathogenic. One of the major pathogenicity criteria is a good correlation of heteroplasmic level with tissue or cellular involvement. Indeed, mtDNA mutations are generally heteroplasmic, which corresponds to the coexistence of normal and mutated molecules in the same cell or tissue, the most affected tissues having a high rate of mutation. On a muscle biopsy of an affected patient, the fibers often present an enzyme deficiency in cytochrome c oxidase (COX-negative) which can be demonstrated in immunohistochemistry. The single fiber study allows to isolate the deficient fibers and to quantify the heteroplasmic rate of a variant. The presence of a high level of heteroplasm in the COX-negative fibers, unlike fibers without deficit, is a strong argument in favor of the pathogenicity of this variant. Currently, this technique is not used routinely in diagnostic laboratories but only occasionally in a research framework in some laboratories. It is a heavy technique that consists of a first stage of laser microdissection of the various muscle fibers followed by a second step of quantification of the variant from each fiber. This second step requires a specific focus for each identified variant.

The aim of this pilot study is to develop a new technique for quantification of single-fiber heteroplasmics isolated by NGS laser microdissection. This, independent of the type of variant, will avoid the long and costly adjustments required for each new variant identified and thus facilitate its use

Publications & conference data

No peer-reviewed publications indexed yet for this trial. Completed trials usually publish results within 12-18 months.