Rapid screening for nuclear genes mutations in isolated respiratory chain complex I defects

Area of Science:

• Biochemistry
• Genetics
• Molecular Biology

Background:

• Complex I (reduced nicotinamide adenine dinucleotide: ubiquinone oxydoreductase) deficiency is the most frequent cause of mitochondrial respiratory chain defects.
• Identifying the molecular basis of complex I deficiencies is challenging due to its dual genetic origin (nuclear and mitochondrial DNA) and limited phenotype-genotype correlations.

Purpose of the Study:

• To develop and validate a rapid screening method for nuclear gene mutations in patients with isolated complex I deficiency.
• To assess the utility of Surveyor nuclease digestion of cDNAs for identifying mutations in frequently implicated nuclear complex I genes.

Main Methods:

• A Surveyor nuclease digestion assay was employed to screen 22 cDNA fragments from eight nuclear complex I genes (NDUFS1, NDUFS2, NDUFS3, NDUFS4, NDUFS7, NDUFS8, NDUFV1, NDUFV2).
• The method was applied to 8 patients with biochemically confirmed complex I deficiency.
• Analysis focused on detecting single nucleotide polymorphisms and missense mutations within the coding sequences.

Main Results:

• The Surveyor nuclease method detected single nucleotide polymorphisms and missense mutations in 18.7% of the analyzed cDNA fragments.
• Molecular defects were identified in 3 out of the 8 patients screened.
• The assay proved to be reliable, easy to interpret, and reduced the number of necessary sequencing reactions.

Conclusions:

• Surveyor nuclease screening is an effective and efficient method for genotyping nuclear gene defects in complex I deficiency.
• This technique can enhance the potential for prenatal diagnosis and improve the understanding of complex I molecular defects.