Mitochondrial gene investigation of LHON in accordance with the diagnostic classification defined in the Certification Criteria for Intractable Diseases

Abstract

Leber’s hereditary optic neuropathy (LHON), one of the mitochondrial diseases, was specified as an intractable disease in 2015. The first three mutations (m.11778G>A, m.3460G>A, m.14484T>C) account for approximately 90% or more of the mitochondrial DNA mutations present in LHON. To detect the primary and other candidate LHON mutations registered in the LHON mutations category of MITOMAP, using Minor Groove Binder (MGB-probe), we measured three primary mutations and conducted sequence analysis at 36 points in nine regions. The results clarified that this type of analysis required time and cost of reagents and generated vast data. In light of the above finding, aiming to improve the investigation efficiency, we conducted the mitochondrial DNA gene investigation in accordance with the diagnostic classification and closely examined the obtained results. Using LHON-like standards in clinical diagnosis prepared by doctors, we judged the breakdown of sixty-three cases. The first three mutations were level L1 for one case, level L2 for nine cases, and level L3 for ten cases, suggesting that the detection rate becomes higher as the diagnostic level increases. The breakdown of nine other mutations showed mutations of level L1 for three cases, level L2 for three cases, and level L3 for four cases. Thus, we achieved labor-saving, shortened reporting frequency (days), and concurrent analysis of the primary and other mutations in the investigation by introducing the mitochondrial DNA gene investigation in accordance with the diagnostic levels in cooperation with the requesting physician. For this reason, the analysis method reported in the present study is expected to be clinically useful in ensuring definitive LHON diagnosis as per the 2015 revision of “Certification Criteria for Intractable Diseases.”