# Mitochondrial functional assays for diagnosis in minimally invasive tissues:optimization and clinical utility

> **NIH NIH U54** · COLUMBIA UNIVERSITY HEALTH SCIENCES · 2020 · $190,103

## Abstract

Project Summary
Primary mitochondrial diseases are characterized by extensive biochemical, clinical, and genetic
heterogeneity, making their analysis complex and the diagnostic process very challenging, lengthy, and
frustrating. Despite rapid progress in identifying a genetic cause using next-generation sequencing, functional
studies showing dysfunction in the mitochondrial respiratory chain are still required in many patients to
complete the diagnosis. Current diagnostic practice involves measurement of respiratory chain enzyme
activities in muscle or liver biopsies, but these assays do not provide a complete analysis of mitochondrial
function and are often avoided due to the invasive nature of the biopsies. Blood sampling and skin biopsy for
fibroblast culture are minimally invasive procedures. In recent years, new mitochondrial functional assays were
developed in the research setting applicable to fibroblasts or even blood cells opening new opportunities, but
the performance in a range of mitochondrial genetic defects and the clinical utility remain unexplored. The goal
of this study is to develop functional testing methods and to establish their clinical utility for the diagnosis and
confirmation of primary mitochondrial disease in minimally invasive tissue with a focus on skin fibroblasts. We
hypothesize that in patients with suspected primary mitochondrial diseases an appropriate panel of tests can
be developed and optimized in fibroblasts (or blood cells) with clinical robustness, good sensitivity and
specificity, to allow for effective mitochondrial function testing with the strategy dependent on functional
category. We will examine a series of mitochondrial functional tests for their diagnostic performance in
fibroblasts of patients with known primary mitochondrial diseases, organized by functional class, and determine
sensitivity and specificity.
Further, we will also examine the effect of differences in tissue culture conditions on the functional test
performance in fibroblasts. Environmental factors reflected in culture conditions such as amino acid abundance
impact these functions with diagnostic and therapeutic implications. Multiple factors in the functionalization of
mitochondrial tRNAs interact with nutritional factors such as amino acids or one-carbon folate esters. In genetic
defects of mitochondrial tRNA aminoacyltransferases (ARS2), which interact with the cognate amino acid,
increasing the amino acid concentration may improve functionality, whereas decreasing its concentration will
exacerbate mitochondrial dysfunction. We will examine the impact of varying the cognate amino acid
concentration for tRNA aminoacylation defects on functional assays. The one-carbon charging of
intramitochondrial folates affects tRNA processes such as formylation of the initiator methionine by MTFMT,
and post transcriptional modification of the wobble base to methyl-uridine or taurinomethyl-uridine in tRNALys
and tRNALeu(UUR), which is affected by...

## Key facts

- **NIH application ID:** 10023968
- **Project number:** 5U54NS078059-10
- **Recipient organization:** COLUMBIA UNIVERSITY HEALTH SCIENCES
- **Principal Investigator:** JOHAN L VAN HOVE
- **Activity code:** U54 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $190,103
- **Award type:** 5
- **Project period:** 2011-09-30 → 2024-08-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10023968

## Citation

> US National Institutes of Health, RePORTER application 10023968, Mitochondrial functional assays for diagnosis in minimally invasive tissues:optimization and clinical utility (5U54NS078059-10). Retrieved via AI Analytics 2026-05-22 from https://api.ai-analytics.org/grant/nih/10023968. Licensed CC0.

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