Optimization of a Multiplex PCR-RFLP Method Used for Detection of Three Primary Mutations in Leber’s Hereditary Optic Neuropathy Patients

Abstract: Leber’s hereditary optic neuropathy (LHON) is the most commonly inherited disease that causes blindness in one or both eyes, with a minimum prevalence of 1 in 31 000 in the northeast of England. What causes LHON is not fully known but three mitochondrial mutations, G3460A, G11778A, and T14484C, have been identified in over 95 % of all LHON patients. To diagnose LHON, detection methods like sequencing, allele specific polymerase chain reaction and polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) are used to identify these three mutations. The methods are now evolving into multiplex ones to increase efficiency, the aim of this study was therefore to optimize one of them, a multiplex PCR-RFLP method developed in 2015. This study was however not completed, due to the COVID-19 pandemic, but a series of preparatory steps were performed before its termination. DNA extraction was performed, both genomic and plasmid, using a kit and in-house protocols. The DNA was then used for polymerase chain reactions (PCRs), for both the human β-globin gene and for the three mutations, where magnesium concentration and annealing temperature was optimized. This study resulted in clear, high quality extractions, with the kit as the preferable method. It also indicated that a 3 mM magnesium concentration and an annealing temperature of 59 °C was optimal for all mutations when using so called LHON primers. The conditions for the PCR using the multiplex primers might be different, therefore a new study is required to evaluate the multiplex PCR-RFLP method further.