Mitochondrial DNA variant discovery in normal-tension glaucoma patients by next-generation sequencing.
OBJECTIVE
Normal-tension glaucoma (NTG) is a disease of late onset, complex trait with multiple risk factors. In this study, we discovered a mitochondrial DNA variant in NTG patients using next-generation sequencing (NGS).


METHODS
The DNA was extracted from the peripheral blood of NTG patients and normal control subjects. Sequencing of the entire mitochondrial DNA (mtDNA) using NGS revealed new genetic risk variants for NTG patients (discovery sample, n = 20). For the candidate genetic variants, we performed a disease-gene association study in the independent case-control populations (validation sample; NTG, n = 196 and normal control, n = 202) using Sanger sequencing.


RESULTS
This study identified 148 different novel mtDNA-sequence changes. Of these, 21 sequence variants identified at a frequency greater than 15% were located in the ND2-ND6, RNR1, RNR2, COX1, COX3, ATP6, ATP8, and CYTB genes. Of the 21 candidate genetic variants, the frequencies of m.4883C>T (ND2 gene), m.9540T>C (COX3 gene), and m.14766C>T (CYTB gene) were significantly different between NTG patients and controls (28.4% vs. 15.3%, P = 0.002; 56.5% vs. 44.4%, P = 0.020; and 3.1% vs. 0.0%, P = 0.030, respectively). The association with m.4883C>T in the ND2 gene resisted the Bonferroni correction for multiple tests. The NTG patients of T genotype in the m.4883C>T variant have more advanced visual field loss than those who carry the C genotype (P = 0.009).


CONCLUSIONS
This study reveals a spectrum of mtDNA variants in patients with NTG. Our results identified a synonymous change, m.4883C>T variant, which was more prevalent in the NTG cohorts than in the controls. This finding suggests that the identified variant may be a genetic risk factor for the development of NTG.
Department of Ophthalmology, Seoul National University Hospital, Seoul, Korea.
Jin Wook
JW
Jeoung
Moon-Woo
MW
Seong
Sung Sup
SS
Park
Dong Myung
DM
Kim
Seok Hwan
SH
Kim
Ki Ho
KH
Park
D004272:DNA, Mitochondrial / Q000235:genetics; D005260:Female; D020869:Gene Expression Profiling; D056726:Genetic Association Studies; D005838:Genotype; D059014:High-Throughput Nucleotide Sequencing; D006801:Humans; D057066:Low Tension Glaucoma / Q000235:genetics*; D008297:Male; D008875:Middle Aged; D009245:NADH Dehydrogenase / Q000235:genetics*; D016133:Polymerase Chain Reaction; D011110:Polymorphism, Genetic; D012307:Risk Factors
D004272:DNA, Mitochondrial; D009245:NADH Dehydrogenase; C521326:NADH dehydrogenase subunit 2, human
genetic variation; mitochondria; mitochondrial DNA; normal-tension glaucoma