Abilities of circumpapillary retinal nerve fiber layer thickness and vascular density to discriminate stages in primary open-angle glaucoma.

PURPOSE: To clarify the abilities of circumpapillary retinal nerve fiber layer thickness (cpRNFLT) obtained by optical coherence tomography (OCT) and circumpapillary vessel density (cpVD) measured by OCT-angiography to distinguish different stages in primary open-angle glaucoma determined by 24-2 or 30-2 static visual field (VF) testing. METHODS: This retrospective study includes 25 healthy normal eyes of 25 subjects and 87 primary open-angle glaucoma eyes of 87 patients. Areas under the receiver operating characteristic curves (AUROC) were evaluated for determining glaucoma stages using cpRNFLT and cpVD. The absolute errors of the estimated mean total deviation (mTD) using optimal models with cpRNFLT and cpVD were also compared. RESULTS: The AUROCs for discriminating glaucomatous eyes from normal eyes was significantly higher for cpRNFLT than the respective AUROCs for cpVD (0.969 [95% CI 0.939 to 0.998] vs. 0.872 [95% CI 0.806 to 0.938], p = 0.006), whereas cpVD had significantly higher AUROC for discriminating severe glaucoma eyes from moderate glaucoma eyes than cpRNFLT (0.771 [95% CI 0.655 to 0.886] vs. 0.578 [95% CI 0.420 to 0.736], p = 0.022). The mean absolute error in estimating mTD using both cpRNFLT and cpVD was significantly less than the error using cpRNFLT alone (4.56 ± 3.76 dB vs. 5.39 ± 4.00 dB, p = 0.027). CONCLUSION: Our results suggest that cpVD is better for follow-ups after moderate stage. The combination of cpRNFLT and cpVD may improve VF estimation compared to cpRNFLT alone.

Evaluation of Bleb Characteristics after Trabeculectomy and Glaucoma Implant Surgery in the Rabbit.

The characteristics of the conjunctival bleb are some of the most important factors for the surgical success of glaucoma filtering surgery. To improve surgical outcome, we investigated bleb histology after 3 different glaucoma surgeries. Surgery was performed in 21 white rabbits. Rabbits were randomized to trabeculectomy or implantation with EX-PRESS or a silicone tube (each n = 7). Bleb survival, intraocular pressure (IOP), and vascularity were evaluated. At 6 weeks, eyes were enucleated for histological analysis. Postoperative IOP at 2 weeks was significantly lower in the trabeculectomy and the EX-PRESS group than in the silicone tube group (p = 0.037) but not thereafter. Postoperative bleb survival (p = 0.542) and vascularity (p = 0.988) were similar among the 3 groups. Histologically, a capsule showing mild fibroblast proliferation associated with intercellular collagen was present around the surgical site. The thickness of the bleb was similar among all experimental groups, but it was significantly greater than in controls (p < 0.05). The inflammatory area did not differ between the EX-PRESS and the silicone tube group but was significantly greater in the trabeculectomy group than in the tube group (p = 0.031). A correlation between the thickness of the bleb wall and inflammation was found (r = 0.56, p < 0.01). EX-PRESS and silicone tube implants appear to be relatively inert, with little difference in biocompatibility and bleb survival. Since some degree of inflammation was still observed histologically in the bleb, more noninvasive surgical methods and more biocompatible materials may be desirable.

Genome-wide association study identifies seven novel susceptibility loci for primary open-angle glaucoma.

Primary open-angle glaucoma (POAG) is the leading cause of irreversible blindness worldwide for which 15 disease-associated loci had been discovered. Among them, only 5 loci have been associated with POAG in Asians. We carried out a genome-wide association study and a replication study that included a total of 7378 POAG cases and 36 385 controls from a Japanese population. After combining the genome-wide association study and the two replication sets, we identified 11 POAG-associated loci, including 4 known (CDKN2B-AS1, ABCA1, SIX6 and AFAP1) and 7 novel loci (FNDC3B, ANKRD55-MAP3K1, LMX1B, LHPP, HMGA2, MEIS2 and LOXL1) at a genome-wide significance level (P < 5.0×10-8), bringing the total number of POAG-susceptibility loci to 22. The 7 novel variants were subsequently evaluated in a multiethnic population comprising non-Japanese East Asians (1008 cases, 591 controls), Europeans (5008 cases, 35 472 controls) and Africans (2341 cases, 2037 controls). The candidate genes located within the new loci were related to ocular development (LMX1B, HMGA2 and MAP3K1) and glaucoma-related phenotypes (FNDC3B, LMX1B and LOXL1). Pathway analysis suggested epidermal growth factor receptor signaling might be involved in POAG pathogenesis. Genetic correlation analysis revealed the relationships between POAG and systemic diseases, including type 2 diabetes and cardiovascular diseases. These results improve our understanding of the genetic factors that affect the risk of developing POAG and provide new insight into the genetic architecture of POAG in Asians.

The long-term outcome of trabeculotomy: comparison with filtering surgery in Japan.

BACKGROUND: To investigate the long-term outcome of trabeculotomy and to compare it with that of trabeculectomy. METHODS: We retrospectively reviewed the medical records of patients who had undergone standalone trabeculotomy. Inclusion criteria included a follow-up period of at least 6 years, availability of reliable static visual field results, etc. Age- and preoperative intraocular pressure -matched trabeculectomy cases served as controls. A Kaplan-Meier analysis was employed as a measure of surgical success. Additional clinical factors were also analyzed. RESULTS: Twenty-five eyes of 25 trabeculotomy patients and 20 eyes of 20 trabeculectomy patients with a mean postoperative follow-up period of 8.0 years were selected. The Kaplan-Meier analysis estimated that the success probability defined as intraocular pressure < 16 mmHg was 44.0 ± 9.9% and 75.0 ± 9.7% at 6 years for trabeculotomy and trabeculectomy, respectively. The final mean deviation significantly progressed in trabeculotomy cases in Central 30-2 programs of the Humphrey Field Analyzer (P = 0.025). Patient characteristics and postoperative clinical data were analyzed by Mann-Whitney's U test and Wilcoxon signed-rank test. CONCLUSIONS: While trabeculotomy was inferior to trabeculectomy in terms of intraocular pressure control and visual field stability in our series, surgical indications should always be determined on an individual basis, pending further research.

Current Status of Glaucoma-related Data Management and Efforts toward Data Standardization.

Purpose: ï¼·e conducted a survey to evaluate the current status of glaucoma-related medical data management and standardization, aiming to improve the development of glaucoma care and research in Japan. Materials and methods: The survey was performed as a paper-based questionnaire of 14 universities that both participate in the glaucoma-related data standardization committee, established by the Japan Glaucoma Society in 2014, and actively perform glaucoma care. Results: All enrolled university hospitals installed an electronic hospital information system and used any of three ophthalmology-limited electronic chart systems. However, only 30.8% of the hospitals established a data extraction system from an electronic medical chart system, and only 14.3% could practically apply medical data for secondary research purposes. In all, 35.7% of the hospitals operate a medical cooperation system with local medical institutions and 42.9% electronically managed medical data inside their departments. Conclusion: This survey clarified the current state of medical data management and standardization.

Enhanced optineurin E50K-TBK1 interaction evokes protein insolubility and initiates familial primary open-angle glaucoma.

Glaucoma is the leading cause for blindness affecting 60 million people worldwide. The optineurin (OPTN) E50K mutation was first identified in familial primary open-angle glaucoma (POAG), the onset of which is not associated with intraocular pressure (IOP) elevation, and is classified as normal-tension glaucoma (NTG). Optineurin (OPTN) is a multifunctional protein and its mutations are associated with neurodegenerative diseases such as POAG and amyotrophic lateral sclerosis (ALS). We have previously described an E50K mutation-carrying transgenic (E50K-tg) mouse that exhibited glaucomatous phenotypes of decreased retinal ganglion cells (RGCs) and surrounding cell death at normal IOP. Further phenotypic analysis of these mice revealed persistent reactive gliosis and E50K mutant protein deposits in the outer plexiform layer (OPL). Over-expression of E50K in HEK293 cells indicated accumulation of insoluble OPTN in the endoplasmic reticulum (ER). This phenomenon was consistent with the results seen in neurons derived from induced pluripotent stem cells (iPSCs) from E50K mutation-carrying NTG patients. The E50K mutant strongly interacted with TANK-binding kinase 1 (TBK1), which prohibited the proper oligomerization and solubility of OPTN, both of which are important for OPTN intracellular transition. Treatment with a TBK1 inhibitor, BX795, abrogated the aberrant insolubility of the E50K mutant. Here, we delineated the intracellular dynamics of the endogenous E50K mutant protein for the first time and demonstrated how this mutation causes OPTN insolubility, in association with TBK1, to evoke POAG.

Overexpression of optineurin E50K disrupts Rab8 interaction and leads to a progressive retinal degeneration in mice.

Glaucoma is one of the leading causes of bilateral blindness affecting nearly 8 million people worldwide. Glaucoma is characterized by a progressive loss of retinal ganglion cells (RGCs) and is often associated with elevated intraocular pressure (IOP). However, patients with normal tension glaucoma (NTG), a subtype of primary open-angle glaucoma (POAG), develop the disease without IOP elevation. The molecular pathways leading to the pathology of NTG and POAG are still unclear. Here, we describe the phenotypic characteristics of transgenic mice overexpressing wild-type (Wt) or mutated optineurin (Optn). Mutations E50K, H486R and Optn with a deletion of the first (amino acids 153-174) or second (amino acids 426-461) leucine zipper were used for overexpression. After 16 months, histological abnormalities were exclusively observed in the retina of E50K mutant mice with loss of RGCs and connecting synapses in the peripheral retina leading to a thinning of the nerve fiber layer at the optic nerve head at normal IOP. E50K mice also showed massive apoptosis and degeneration of entire retina, leading to approximately a 28% reduction of the retina thickness. At the molecular level, introduction of the E50K mutation disrupts the interaction between Optn and Rab8 GTPase, a protein involved in the regulation of vesicle transport from Golgi to plasma membrane. Wt Optn and an active GTP-bound form of Rab8 complex were localized at the Golgi complex. These data suggest that alternation of the Optn sequence can initiate significant retinal degeneration in mice.

Genetic variants associated with glaucomatous visual field loss in primary open-angle glaucoma.

Primary open-angle glaucoma (POAG) is characterized by a progressive optic neuropathy with visual field loss. To investigate the genetic variants associated with visual field loss in POAG, Japanese POAG patients (n = 426) and control subjects (n = 246) were genotyped for 22 genetic variants predisposing to POAG that can be classified into those associated with intraocular pressure (IOP) elevation (IOP-related genetic variants) and optic nerve vulnerability independent of IOP (optic nerve-related genetic variants). The genetic risk score (GRS) of the 17 IOP-related and five optic nerve-related genetic variants was calculated, and the associations between the GRS and the mean deviation (MD) of automated static perimetry as an indicator of the severity of visual field loss and pattern standard deviation (PSD) as an indicator of the focal disturbance were evaluated. There was a significant association (Beta = - 0.51, P = 0.0012) between the IOP-related GRS and MD. The severity of visual field loss may depend on the magnitude of IOP elevation induced by additive effects of IOP-related genetic variants. A significant association (n = 135, Beta = 0.65, P = 0.0097) was found between the optic nerve-related, but not IOP-related, GRS and PSD. The optic nerve-related (optic nerve vulnerability) and IOP-related (IOP elevation) genetic variants may play an important role in the focal and diffuse visual field loss respectively. To our knowledge, this is the first report to show an association between additive effects of genetic variants predisposing to POAG and glaucomatous visual field loss, including severity and focal/diffuse disturbance of visual field loss, in POAG.

Investigation of the association between SLC1A3 gene polymorphisms and normal tension glaucoma.

PURPOSE: To investigate whether the solute carrier family 1, member 3 (SLC1A3) gene, which encodes the glutamate aspartate transporter, is associated with normal tension glaucoma (NTG) in Japanese patients. METHODS: Two hundred and ninety-five Japanese patients with NTG and 518 Japanese healthy controls were recruited. Patients exhibiting comparatively early NTG onset were selected because early onset suggests that genetic factors may show stronger involvement. We genotyped 5 single-nucleotide polymorphisms (SNPs) in SLC1A3 and assessed the allelic and genotypic diversity among cases and controls. RESULTS: There were no statistically significant differences in the frequency of SLC1A3 alleles and genotypes between cases and controls. CONCLUSIONS: Our study showed no association between SLC1A3 and NTG, suggesting that the SLC1A3 gene may not be an associated factor in NTG pathogenesis.

Genotyping HLA-DRB1 and HLA-DQB1 alleles in Japanese patients with normal tension glaucoma.

PURPOSE: Normal tension glaucoma (NTG) is a subtype of glaucoma in which intraocular pressure is within the statistically normal range. NTG may be associated with an immune disorder. The aim of this study was to determine whether specific alleles in the human leukocyte antigen (HLA)-DRB1 and HLA-DQB1 genes correlated with NTG in Japanese patients. METHODS: We genotyped the HLA-DRB1 and HLA-DQB1 alleles in 113 Japanese patients with NTG and in 184 healthy Japanese control subjects using the polymerase chain reaction-sequence-specific oligonucleotide probes (PCR-SSOP) Luminex method. We assessed the allelic diversity in patients and controls. RESULTS: There were no statistically significant differences in the allele frequency of HLADRB1 and HLA-DQB1 between NTG patients and control subjects, and no HLA-DRB1-HLA-DQB1 haplotypes demonstrated any significant association with NTG. CONCLUSIONS: Our findings suggest that HLA-DRB1 and HLA-DQB1 polymorphisms have no significant effect on the development of NTG in Japanese patients.

Analysis of microsatellite polymorphisms within the GLC1F locus in Japanese patients with normal tension glaucoma.

PURPOSE: To investigate whether the GLC1F locus is associated with normal tension glaucoma (NTG) in Japanese patients. METHODS: We recruited 242 unrelated Japanese subjects, including, 141 NTG patients and 101 healthy controls. The patients exhibiting a comparatively early onset were selected as they suggest that genetic factors may show stronger involvement. Genotyping and assessment of allelic diversity was performed on 11 highly polymorphic microsatellite markers in and around the GLC1F locus. RESULTS: Individuals carrying the 163 allele of D7S1277i had a statistically significant increased risk of NTG (p=0.0013, pc=0.016, OR=2.47, 95%CI=1.42-4.30). None of the other markers identified significant loci (pc>0.05) after Bonferroni's correction. CONCLUSIONS: These findings suggested that the genes in the GLC1F locus may be associated with the pathogenesis of NTG.

Association between genetic polymorphisms of adrenergic receptor and diurnal intraocular pressure in Japanese normal-tension glaucoma.

PURPOSE: To evaluate the relationship between genetic polymorphisms of the adrenergic receptor (ADR) and diurnal intraocular pressure (IOP) in Japanese normal-tension glaucoma (NTG) patients. DESIGN: Prospective, comparative case series. PARTICIPANTS: Ninety-two untreated NTG patients. METHODS: The IOP of both eyes was measured at 3-hour intervals from 0600 to 2400 hours over 2 consecutive days. We used IOP data from the eye with the greater visual field defect for statistical analysis. The mean IOP over 2 days was used for each time point. Genetic polymorphisms in α1A-, α2A-, α2B-, α2C-, ß1-, ß2-, and ß3-ADR were determined mainly by direct DNA sequencing. The relationship between IOP and genetic polymorphisms was analyzed. MAIN OUTCOME MEASURES: The IOP and genotypes of genetic polymorphisms. RESULTS: Diurnal mean IOP of the subjects was 14.8 ± 2.1 mmHg (mean value ± standard deviation). For Del 301-303 in α2B-ADR, insertion/insertion (I/I) had a significantly higher diurnal mean IOP (P = 0.017), peak IOP (P = 0.038), and trough IOP (P = 0.046) than deletion (D) carriers. For Del 322-325 in α2C-ADR, I/I had a significantly lower diurnal mean IOP (P = 0.037) and peak IOP (P = 0.029) than D carriers. For S49G (A/G) in ß1-ADR, A/A had a significantly higher diurnal mean IOP (P = 0.023), peak IOP (P = 0.019), and trough IOP (P = 0.014) than G carriers. For these 3 polymorphisms, repeated measures analysis of variance showed that the major homozygotes and minor carriers had parallel diurnal IOP curves, but significantly different diurnal IOP levels. CONCLUSIONS: Polymorphisms of the ADR gene may alter the untreated IOP level of patients with NTG.

[Long-acting carteolol hydrochloride 2% ophthalmic solution phase IV study--investigation of the effectiveness, safety and plasma concentration].

PURPOSE: We investigated the effectiveness, safety and plasma concentration of long-acting carteolol hydrochloride 2% ophthalmic solution (LA) as compared with the original carteolol hydrochloride 2% ophthalmic solution(CA). METHODS: Patients with primary open angle glaucoma and ocular hypertension were randomized to 62 patients of LA group (LA once a day) and 62 patients of CA group (CA twice a day) in this multicenter, open-label trial. The intraocular pressure (IOP), pulse rate, blood pressure and plasma concentration were examined for 8 weeks. RESULTS: The IOP reduction and reduction rate were not significant at any point between the two groups. Systolic blood pressure decreased significantly in both groups, however, diastolic blood pressure decreased only in the CA group. The plasma concentration of the LA group was significantly lower than that of the CA group. CONCLUSIONS: The IOP reduction effect of the LA group was the same as the CA group. This study suggests that long-acting treatment with alginic acid can be useful for reducing systemic side effects.

A case of childhood glaucoma with a combined partial monosomy 6p25 and partial trisomy 18p11 due to an unbalanced translocation.

Background: Chromosomal deletion involving the 6p25 region results in a clinically recognizable syndrome characterized by anterior eye chamber anomalies with risk of glaucoma and non-ocular malformations (6p25 deletion syndrome). We report a newborn infant case of childhood glaucoma with a combination of partial monosomy 6p25 and partial trisomy 18p11 due to an unbalanced translocation.Materials and methods: The patient was a 0-year-old girl. Both eyes showed aniridia and left eye Peters anomaly with multiple malformations. To identify the chromosomal aberrations in the patient with clinically suspected 6p25 deletion syndrome, we performed cytogenetic analysis (G-banding and multicolor fluorescent in-situ hybridization) and array-based comparative genomic hybridization (array-CGH) analysis.Results: Cytogenetic analyses revealed a derivative chromosome 6 with its distal short arm replaced by an extra copy of the short arm of chromosome 18. Array-CGH analysis detected a 4.6-Mb deletion at 6pter to 6p25.1 and 8.9-Mb duplication at 18pter to 18p11.22. To determine the breakpoint of the unbalanced rearrangement at the single-base level, we performed a long-range PCR for amplifying the junctional fragment of the translocation breakpoint. By sequencing the junctional fragment, we defined the unbalanced translocation as g.chr6:pter_4594783delinschr18:pter_8911541.Conclusions: A phenotype corresponding to combined monosomy 6p25 and trisomy 18p11 presented as childhood glaucoma associated with non-acquired (congenital) ocular anomalies consist of aniridia and Peters anomaly and other systemic malformations. To the best of our knowledge, this is the first report which demonstrated the breakpoint sequence of an unbalanced translocation in a Japanese infant with childhood glaucoma.

Genetic Variants Associated With the Onset and Progression of Primary Open-Angle Glaucoma.

PURPOSE: We sought to investigate the genetic variants associated with the onset and progression of primary open-angle glaucoma (POAG). DESIGN: Case-control genetic association study. METHODS: Japanese POAG patients (n = 505) and control subjects (n = 246) were genotyped for 22 genetic variants predisposing to POAG that can be classified into those associated with intraocular pressure (IOP) elevation (IOP-related genetic variants) and optic nerve vulnerability independent of IOP (non-IOP-related genetic variants). The total number of risk alleles of the 17 IOP-related and 5 non-IOP-related genetic variants were calculated as the genetic risk score (GRS), and the associations between the GRS and family history of glaucoma as an indicator of POAG onset and age at the diagnosis of glaucoma as an indicator of POAG progression were evaluated. RESULTS: There was a significant association (P = .014; odds ratio 1.26 per GRS) between the non-IOP-related GRS, but not IOP-related GRS, and a family history of glaucoma in POAG. As the non-IOP-related GRS increased, the risk of a family history of glaucoma increased. In contrast, a significant association (P = .0014; ß = -0.14) was found between the IOP-related GRS, but not non-IOP-related GRS, and age at the diagnosis of glaucoma. As the IOP-related GRS increased, age at the diagnosis of glaucoma decreased. CONCLUSION: The results indicate that non-IOP-related (optic nerve vulnerability) rather than IOP-related (IOP elevation) genetic variants may play an important role in the onset of POAG (family history of glaucoma) and that IOP-related rather than non-IOP-related genetic variants may play an important role in its progression (age at the diagnosis of glaucoma).

Association of toll-like receptor 2 gene polymorphisms with normal tension glaucoma.

PURPOSE: Toll-like receptor 2 (TLR2) is a transmembrane receptor that mediates immune responses to exogenous and endogenous ligands, and interacts with heat-shock proteins, which are reportedly involved in normal tension glaucoma (NTG). We investigated whether TLR2 polymorphisms are associated with NTG. METHODS: 200 Japanese patients with NTG and 128 healthy Japanese controls were recruited. We genotyped five single-nucleotide polymorphisms (SNPs) in the TLR2 gene and assessed the allele and haplotype diversities between cases and controls for all SNPs. RESULTS: No significant differences in the frequency of TLR2 alleles and haplotypes in the NTG cases were detected, compared with the controls. CONCLUSIONS: Our study showed no evidence for an association between TLR2 polymorphisms and NTG. TLR2 polymorphisms may not play an important role in NTG pathogenesis in the Japanese population.

Postoperative outcome of three different procedures for childhood glaucoma.

PURPOSE: To investigate the long-term postoperative outcome of three surgical procedures for childhood glaucoma. PATIENTS AND METHODS: In this retrospective study, the patients were divided into a goniotomy group, a trabeculotomy group, and a filtering surgery group, based on the initial surgical procedure. Failure was defined as an IOP ≥21 mmHg with medication at two consecutive visits. A Kaplan-Meier analysis was applied to calculate the probability of success. Additional metrics included IOP, number of additional operations, eye drop scores, and visual acuity. RESULTS: We studied 40 eyes of 25 patients, 21 eyes of 15 patients, and 12 eyes of 7 patients in the goniotomy, trabeculotomy, and filtering surgery groups, respectively. The 10- and 20-year probability of success was 65.2% and 65.2%, 42.2% and NA (no data for 20 years), and 91.7% and 80.2% for the goniotomy, trabeculotomy, and filtering surgery groups, respectively. CONCLUSION: All three procedures maintained an IOP of less than 21 mmHg for up to 10 years in 65.2%, 42.2%, and 91.7% of childhood glaucoma cases.

Effect of Timolol on Optineurin Aggregation in Transformed Induced Pluripotent Stem Cells Derived From Patient With Familial Glaucoma.

Purpose: To determine a chemical agent that can reduce the aggregation of optineurin (OPTN) in cells differentiated from induced pluripotent stem cells obtained from a patient with normal-tension glaucoma (NTG) caused by an E50K mutation in the OPTN gene (OPTNE50K-NTG). Methods: Retinal ganglion cells (RGCs) were created from induced pluripotent stem cells derived from a healthy individual (wild-type [WT]-iPSCs) and from a patient with NTG due to OPTNE50K (E50K-iPSCs) mutation. The death of the induced RGCs was evaluated by counting the number of TUNEL- and ATH5-positive cells. Axonal growth was determined by measuring the axonal length of TUJ1-positive cells. OPTN aggregation was assessed by measuring the OPTN-positive area by immunofluorescence and by Western blotting. Autophagic flux assay was investigated by determining the light chain 3 (LC3)B-II/LC3B-I ratio and p62 expression by Western blotting. Results: The results showed OPTNE50K aggregation, activation of astrocytes, reduction in the number of RGCs, and enhancement of apoptotic cell death in the in vitro OPTNE50K model of NTG. Timolol was found to reduce the OPTNE50K-positive area and decreased the insoluble OPTNE50K, suggesting that it has the potential of reducing the OPTNE50K aggregation. Timolol also increased the ATH5-positive cells, decreased TUNEL-positive cells, increased the LC3B-II/LC3B-I ratio, and decreased the expression of p62. These findings suggest that timolol might enhance autophagic flux, leading to reduced OPTNE50K aggregation. Conclusions: Timolol should be considered a potential therapeutic agent specific to OPTNE50K-NTG because it can reduce the OPTNE50K aggregation in E50K-iPSCs-RGCs by enhancing autophagic flux and neuroprotective effects.

Genomic Organization of TBK1 Copy Number Variations in Glaucoma Patients.

BACKGROUND: Approximately 1% of normal tension glaucoma (NTG) cases are caused by TANK-binding kinase 1 (TBK1) gene duplications and triplications. However, the precise borders and orientation of these TBK1 gene copy number variations (CNVs) on chromosome 12 are unknown. METHODS: We determined the exact borders of TBK1 CNVs and the orientation of duplicated or triplicated DNA segments in 5 NTG patients with different TBK1 mutations using whole-genome sequencing. RESULTS: Tandemly duplicated chromosome segments spanning the TBK1 gene were detected in 4 NTG patients, each with unique borders. Four of 5 CNVs had borders located within interspersed repetitive DNA sequences (Alu and long interspersed nuclear element-L1 elements), suggesting that mismatched homologous recombinations likely generated these CNVs. A fifth NTG patient had a complex rearrangement including triplication of a chromosome segment spanning the TBK1 gene. CONCLUSIONS: No specific mutation hotspots for TBK1 CNVs were detected, however, interspersed repetitive sequences (ie, Alu elements) were identified at the borders of TBK1 CNVs, which suggest that mismatch of these elements during meiosis may be the mechanism that generated TBK1 gene dosage mutations.