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Updated: Aug 16, 2026
Genotyping Single Nucleotide Polymorphisms in the Mitochondrial Genome by Pyrosequencing
Published on: February 10, 2023
Screening for mitochondrial DNA heteroplasmy in children at risk for mitochondrial disease
M Ito1, S Tran Le, D Chaudhari
1Division of Medical Genetics, Childrens Hospital Los Angeles, Los Angeles, CA 90027, USA.
Insights
Mitochondrial DNA (mtDNA) heteroplasmy, particularly in the control region, is significantly associated with neuromuscular and multi-system dysfunction in children. This finding suggests mtDNA variants may serve as crucial disease markers or pathological mutations.
Area of Science:
- Mitochondrial Genetics
- Human Genetics
- Molecular Biology
Background:
- Mitochondrial DNA (mtDNA) mutations are implicated in various diseases.
- Heteroplasmy, the coexistence of different mtDNA types, is a known factor in disease pathogenesis.
- The mitochondrial control region (CR) is crucial for mtDNA replication and transcription but is less studied in disease contexts.
Purpose of the Study:
- To investigate the prevalence of mtDNA heteroplasmy in children with neuromuscular and/or multi-system dysfunction and elevated lactate levels.
- To identify potential novel mtDNA variants associated with these conditions.
- To determine if heteroplasmy in the CR is a significant marker for these pediatric diseases.
Main Methods:
- Temporal temperature gradient gel electrophoresis (TTGE) was used to screen 70% of the mtDNA, including all 22 transfer RNA (tRNA) genes.
- Standard Polymerase Chain Reaction/Allele Specific Oligonucleotide (PCR/ASO) and Southern analyses were also employed.
- Sequencing of identified heteroplasmic variants.
Main Results:
- Heteroplasmy was detected in 22 out of 75 patients and 2 out of 95 controls (P < 0.001), excluding common length variants.
- Four patients exhibited heteroplasmy at two distinct locations.
- Of 23 sequenced heteroplasmic variants in patients, 17 were novel point variants in the CR, with only two involving tRNA genes.
Conclusions:
- Mitochondrial DNA heteroplasmy is highly associated with the studied pediatric disease group.
- Heteroplasmy is predominantly found in the mtDNA control region, suggesting its importance in disease.
- The identified novel CR variants may represent pathological mutations or valuable disease markers for neuromuscular and multi-system dysfunction.
Abstract:
Temporal temperature gradient gel electrophoresis was used to screen 70% of the mtDNA, including all 22 tRNA genes, for heteroplasmy in 75 children with neuromuscular and/or multi-system dysfunction and elevated lactate levels, and in 95 controls. Standard PCR/ASO (allele specific oligonucleotide) and Southern analyses were also employed. Excluding common length variants, heteroplasmy was found in 22 patients and two controls (P < 0.001), with four patients demonstrating heteroplasmy in two locations each. Of the 23 heteroplasmic variants sequenced among the patients, 17 were novel point variants in the control region (CR) and only two involved tRNA genes. Heteroplasmy is highly associated with the disease group, and is predominately found in the CR, an area rarely studied in patient populations. These variants may be pathological mutations or disease markers.
