Identification of genetic variants associated with Huntington's disease progression: a genome-wide association study

Background Huntington's disease is caused by a CAG repeat expansion in the huntingtin gene, HTT. Age at onset has been used as a quantitative phenotype in genetic analysis looking for Huntington's disease modifiers, but is hard to define and not always available. Therefore, we aimed to generate a novel measure of disease progression and to identify genetic markers associated with this progression measure. Methods We generated a progression score on the basis of principal component analysis of prospectively acquired longitudinal changes in motor, cognitive, and imaging measures in the 218 indivduals in the TRACK-HD cohort of Huntington's disease gene mutation carriers (data collected 2008–11). We generated a parallel progression score using data from 1773 previously genotyped participants from the European Huntington's Disease Network REGISTRY study of Huntington's disease mutation carriers (data collected 2003–13). We did a genome-wide association analyses in terms of progression for 216 TRACK-HD participants and 1773 REGISTRY participants, then a meta-analysis of these results was undertaken. Findings Longitudinal motor, cognitive, and imaging scores were correlated with each other in TRACK-HD participants, justifying use of a single, cross-domain measure of disease progression in both studies. The TRACK-HD and REGISTRY progression measures were correlated with each other (r=0·674), and with age at onset (TRACK-HD, r=0·315; REGISTRY, r=0·234). The meta-analysis of progression in TRACK-HD and REGISTRY gave a genome-wide significant signal (p=1·12 × 10−10) on chromosome 5 spanning three genes: MSH3, DHFR, and MTRNR2L2. The genes in this locus were associated with progression in TRACK-HD (MSH3 p=2·94 × 10−8 DHFR p=8·37 × 10−7 MTRNR2L2 p=2·15 × 10−9) and to a lesser extent in REGISTRY (MSH3 p=9·36 × 10−4 DHFR p=8·45 × 10−4 MTRNR2L2 p=1·20 × 10−3). The lead single nucleotide polymorphism (SNP) in TRACK-HD (rs557874766) was genome-wide significant in the meta-analysis (p=1·58 × 10−8), and encodes an aminoacid change (Pro67Ala) in MSH3. In TRACK-HD, each copy of the minor allele at this SNP was associated with a 0·4 units per year (95% CI 0·16–0·66) reduction in the rate of change of the Unified Huntington's Disease Rating Scale (UHDRS) Total Motor Score, and a reduction of 0·12 units per year (95% CI 0·06–0·18) in the rate of change of UHDRS Total Functional Capacity score. These associations remained significant after adjusting for age of onset. Interpretation The multidomain progression measure in TRACK-HD was associated with a functional variant that was genome-wide significant in our meta-analysis. The association in only 216 participants implies that the progression measure is a sensitive reflection of disease burden, that the effect size at this locus is large, or both. Knockout of Msh3 reduces somatic expansion in Huntington's disease mouse models, suggesting this mechanism as an area for future therapeutic investigation

Pooled retrospective analysis of 70 mg erenumab in episodic and chronic migraine: a two tertiary headache centers experience during clinical practice

Erenumab is a monoclonal antibody, targeted against the calcitonin gene-related peptide (CGRP) receptor. Clinical studies have demonstrated prophylactic efficacy in both episodic (EM) and chronic migraine (CM). The aim of the present study is to evaluate the efficacy of treatment in tertiary headache centers under real-life conditions. In a retrospective analysis, the period of 3 months before and after initiation of erenumab therapy was compared. Relevant parameters (headache days, headache intensity, headache duration, acute medication, previous prophylaxis treatments) were collected from medical charts of all migraine patients (N = 82) who started treatment with erenumab between November 1st 2018 and May 1st 2019 at two tertiary headache centers in Germany. The sample included 68 female (82.9%) and 14 male patients aged between 22 and 78 years (mean 51.1 years, SD 10.5 years). Of these patients, 57.3% met the criteria for CM and 56.9% overused acute medication. Under therapy with erenumab, a significant reduction of headache days was observed from the first month on. The effect was most pronounced in the third month with a decrease in monthly headache days from 16.6 to 11.6 days (p < 0.001). There was also a significant reduction in reported headache intensity (p = 0.004) and average duration of headache attacks (p = 0.016). The 50% responder rate in patients with CM was lower in the first month compared to EM but then increased similarly to EM. Patients with medication overuse (MO) also responded to the therapy. There was a reduction in medication overuse from 57% at baseline to 29% after therapy (p = 0.011). Overall, a positive result of treatment with erenumab can be shown in a highly selected sample with severely affected migraine patients and a refractory course prior to treatment. This re-confirms the clinical trial data also for this highly selected group

Choroidal Flow Signal in Late-Onset Stargardt Disease and Age-Related Macular Degeneration: An OCT-Angiography Study

PURPOSE. To investigate the choroidal blood flow in areas within and adjacent to retinal pigment epithelium (RPE) atrophy secondary to late-onset Stargardt disease (STGD1) and age-related macular degeneration (AMD). METHODS. A total of 43 eyes (23 STGD1 and 20 AMD) of patients with RPE atrophy and 25 eyes of healthy controls without ocular pathology underwent multimodal imaging including optical coherence tomography angiography (OCT-A; PLEX Elite 9000 Swept-Source OCT). Using an exploratory approach, choriocapillaris and deeper choroid OCT-A slabs were evaluated in order to detect differences between STGD1 and AMD. The magnitude of absence-of-flow signal (AFS) was investigated in terms of area-fraction and size-frequency distribution. RESULTS. Qualitative and quantitative analysis of areas of RPE atrophy revealed more pronounced rarefaction of the choriocapillaris flow signal in STGD1 as compared to AMD (AFS area fraction: 33.15% +/- 6.86% vs. 31.68% +/- 8.39%; P = 0.517), while outside RPE atrophy rarefaction was less pronounced in STGD1 (AFS area fraction: 17.41% +/- 5.67% vs. 21.59% +/- 6.90%; P < 0.001), to the level of nonsignificance compared to controls (13.27% +/- 2.99%, P = 0.368). Given this discrepancy, the ratio of the AFS area fraction within/outside of RPE atrophy could be used to differentiate between STGD1 and AMD with 65.0% sensitivity and 92.3% specificity. CONCLUSIONS. Using OCT-A, comparison of choroidal flow signal within and outside the area of RPE atrophy revealed distinct differences between STGD1 and AMD, potentially implicating a differential role of the choroid in the pathogenesis of RPE atrophy in these two diseases

Artificial intelligence for morphology-based function prediction in neovascular age-related macular degeneration

Spatially-resolved mapping of rod- and cone-function may facilitate monitoring of macular diseases and serve as a functional outcome parameter. However, mesopic and dark-adapted two-color fundus-controlled perimetry (FCP, also called "microperimetry") constitute laborious examinations. We have devised a machine-learning-based approach to predict mesopic and dark-adapted (DA) retinal sensitivity in eyes with neovascular age-related macular degeneration (nAMD). Extensive psychophysical testing and volumetric multimodal retinal imaging data were acquired including mesopic, DA red and DA cyan FCP, spectral-domain optical coherence tomography and confocal scanning laser ophthalmoscopy infrared reflectance and fundus autofluorescence imaging. With patient-wise leave-one-out cross-validation, we have been able to achieve prediction accuracies of (mean absolute error, MAE [95% CI]) 3.94 dB [3.38, 4.5] for mesopic, 4.93 dB [4.59, 5.27] for DA cyan and 4.02 dB [3.63, 4.42] for DA red testing. Partial addition of patient-specific sensitivity data decreased the cross-validated MAE to 2.8 dB [2.51, 3.09], 3.71 dB [3.46, 3.96], and 2.85 dB [2.62, 3.08]. The most important predictive feature was outer nuclear layer thickness. This artificial intelligence-based analysis strategy, termed "inferred sensitivity", herein, enables to estimate differential effects of retinal structural abnormalities on cone- and rod-function in nAMD, and may be used as quasi-functional surrogate endpoint in future clinical trials

Light sensitivity within areas of geographic atrophy secondary to age-related macular degeneration

Purpose: To investigate residual sensitivity within geographic atrophy (GA) secondary to age-related macular degeneration. Methods: Mesopic and dark-adapted (DA) cyan and red light sensitivity (Goldmann III) were investigated using fundus-controlled perimetry (microperimetry). Test points were placed within GA along an “iso-hull” with a distance of −0.645° to the atrophy boundary. The false-positive response rate was determined with suprathreshold stimuli to the optic disc (Heijl-Krakau method) and used to compute the expected sensitivity measurements for the assumption of absolute scotomata. The outermost visible retinal layer on spectral-domain optical coherence tomography at the location of each test point was determined. Results: Thirty eyes of 36 patients (75.55 ± 7.93 years; 19 female) from the prospective natural history study Directional Spread in Geographic Atrophy (NCT02051998), with a total of 1380 threshold determinations were analyzed. The measured sensitivities were significantly (P < 0.01) higher than the expected values for absolute scotomata (mean ± standard error of +6.92 ± 0.86 dB for mesopic, +2.57 ± 0.56 dB for DA cyan, and +4.93 ± 0.74 dB for DA red testing). For mesopic testing and DA red testing, the presence of a residual outer nuclear layer had a significant effect on this discrepancy (P < 0.001). There was no effect of fixation stability or any other reliability index on this discrepancy. Conclusions: Measured sensitivities within the inner junctional zone of GA may not be purely explained by patient-specific false-positive response rates or other reliability indices. The marked influence of the outer retinal configuration on measured sensitivity may be indicative of residual cone function within GA at the inner junctional zone

Type 1 Choroidal Neovascularization Is Associated with Reduced Localized Progression of Atrophy in Age-Related Macular Degeneration.

PURPOSE To investigate the association between the presence of type 1 choroidal neovascularization (CNV) and the localized progression of atrophy in age-related macular degeneration (AMD). DESIGN Analysis of patients' data collected in the context of 2 noninterventional, prospective studies conducted at the Department of Ophthalmology, University of Bonn, Germany. PARTICIPANTS A total of 98 eyes diagnosed with AMD of 59 patients (40 female, 19 male) with a mean (±standard deviation) age at baseline of 76.60±6.65 years and median (interquartile range) review period of 1.17 years (1.01-1.55) were included. Eyes were subdivided into 3 categories based on multimodal imaging and ocular history: retinal pigment epithelium (RPE) atrophy with treatment-naïve quiescent CNV (n=7), RPE atrophy with a history of exudative CNV (n=10), and RPE atrophy without evidence of coexisting CNV (n=81). METHODS Retinal pigment epithelium atrophy was delineated on the basis of serial fundus-autofluorescence and infrared-reflectance images. If CNV was detected by OCT angiography (OCTA), its location and dimension were spatially mapped to RPE atrophy. The localized progression of RPE atrophy in topographic relation to the CNV lesion was then analyzed using mixed-effects logistic regression. The spatial overlap (Dice coefficient) between predicted and observed RPE atrophy progression was evaluated to estimate the model accuracy. MAIN OUTCOME MEASURES Odds ratio (OR) for localized RPE atrophy progression in areas overlying type 1 CNV. RESULTS The prediction model achieved a high overlap between predicted and observed RPE atrophy progression with a cross-validated Dice coefficient of 0.87 (95% confidence interval [CI], 0.85-0.89) reflecting a high accuracy. The odds for future RPE atrophy involvement were reduced by a factor of 0.21 (95% CI, 0.19-0.24) in the presence of treatment-naïve quiescent type 1 CNV and by a factor of 0.46 (95% CI, 0.41-0.51) in the presence of exudative type 1 CNV. CONCLUSIONS The results indicate that there is markedly reduced RPE atrophy progression in areas co-localizing with quiescent and exudative type 1 CNV. This observation is compatible with a potential protective effect of type 1 CNV on the RPE and overlying neurosensory retina. These results may have relevant clinical implications for the management of CNV and lead to new therapeutic strategies to prevent atrophy progression

The STArgardt Remofuscin Treatment Trial (STARTT): Design and baseline characteristics of enrolled Stargardt patients

Background: This report describes the study design and baseline characteristics of patients with Stargardt disease (STGD1) enrolled in the STArgardt Remofuscin Treatment Trial (STARTT). Methods: In total, 87 patients with genetically confirmed STGD1 were randomized in a double-masked, placebo-controlled proof of concept trial to evaluate the safety and efficacy of 20 milligram oral remofuscin for 24 months. The primary outcome measure is change in mean quantitative autofluorescence value of an 8-segment ring centred on the fovea (qAF 8). Secondary efficacy variables are best corrected visual acuity (BCVA), low-luminance visual acuity (LLVA), mesopic microperimetry (mMP), spectral domain optical coherence tomography (SD-OCT), reading speed on Radner reading charts, and patient-reported visual function as assessed by the National Eye Institute Visual Functioning Questionnaire 25 (NEI VFQ-25) and Functional Reading Independence (FRI) Index. Results: Mean age of participants was 35±11 years with 49 (56%) female. Median qAF 8 value was 438 Units (range 210-729). Median BCVA and LLVA in decimal units were 0.50 (range 0.13-0.80) and 0.20 (range 0.06-0.63), respectively. The median of the mean retinal sensitivity with mMP was 20.4 dB (range 0.0-28.8). SD-OCT showed median central subfield retinal thickness of 142 m (range 72-265) and median macular volume of 1.65 mm 3 (range 1.13-2.19). Compared to persons without vision impairment, both reading performance and patient-reported visual function were significantly lower (p<0.001, one sample t-test). Mean reading speed was 108±39 words/minute with logRAD-score of 0.45±0.28. Mean VFQ-25 composite score was 72±13. Mean FRI Index score 2.8±0.6. Conclusions: This trial design may serve as reference for future clinical trials as it explores the utility of qAF 8 as primary outcome measure. The baseline data represent the largest, multi-national, STGD1 cohort to date that underwent standardized qAF imaging, reading speed assessment and vision-related quality of life measures which all contribute to the characterization of STGD1