Exploring rare differences in mitochondrial genome between MZ twins using Ion Torrent semiconductor sequencing.

Area of Science:

• Forensic Science
• Genetics
• Molecular Biology

Background:

• Monozygotic (MZ) twins share identical nuclear DNA, posing challenges for forensic differentiation.
• Mitochondrial DNA (mtDNA) has higher mutation rates than nuclear DNA due to limited repair mechanisms.
• Previous research explored nuclear genome mutations and mtDNA variants in MZ twins' blood.

Purpose of the Study:

• To investigate minor differences in mitochondrial genomes (mtGenomes) between MZ twins across different tissue types.
• To assess the efficacy of mtGenome sequencing for differentiating MZ twins.
• To identify which tissue type is most prone to accumulating mtGenome variations in MZ twins.

Main Methods:

• Utilized Ion Torrent semiconductor sequencing with a commercial mtGenome sequencing kit.
• Analyzed three tissue types (blood, saliva, hair shaft) from seven sets of MZ twins.
• Focused on identifying point heteroplasmy (PHP) and nucleotide variants in the mtGenomes.

Main Results:

• Point heteroplasmy (PHP) was detected in blood (1 set) and saliva (2 sets) of MZ twins.
• PHP was present in all seven sets of MZ twins' hair shaft samples.
• The coding region of the mtGenome showed more PHPs than the control region.

Conclusions:

• mtGenome sequencing is a competent method for differentiating MZ twins.
• Hair shaft samples are most likely to accumulate the minor mtGenome differences needed for MZ twin differentiation.
• Findings support the use of mtGenome sequencing in forensic applications involving MZ twins.