Mitochondrial DNA variation and intervertebral disc degeneration: a genotypic analysis in a South African cohort

Non-communicable diseases are multifactorial in that they can be caused by genetic factors, age, sex and poor lifestyle choices. They are estimated to account for 71% of deaths globally with 80% of these deaths occurring in low- and middle-income countries. This is particularly true for Intervertebral Disc Degeneration associated with mitochondrial dysfunction. Interestingly, mitochondrial dysfunction can arise from mutations in both the nuclear and the mitochondrial genomes. The present study, therefore, aimed to determine if there is an association between mitochondrial DNA mutations associated with mitochondrial dysfunction and disc degeneration in a South African cohort, and in addition, generate genetic data for understudied mutations in African populations.

Mutations were selected using a systematic literature review. DNA was collected using buccal swabs and extracted using a standard salt-lysis protocol. Mass-array genotyping was done for previously reported as well as novel mutations. GenAlEx (version 6.5), RStudio and SHEsis were used for statistical analyses. Although no significant associations were found, the identified polymorphic mutations C16223T, A10398G and A8536G were found to have higher mutant allele frequencies in case individuals indicating that had a larger cohort been used, significance may have been observed.

This study was able to generate genotypic information for a South African cohort for both reported and understudied mutations. Furthermore, the identification of higher mutant allele frequencies for C16223T, A10398G and A8536G highlights the importance of considering these mutations in future studies using a larger cohort.