Characterization of the Frmd7 Knock-Out Mice Generated by the EUCOMM/COMP Repository as a Model for Idiopathic Infantile Nystagmus (IIN)

In this study, we seek to exclude other pathophysiological mechanisms by which Frmd7 knock-down may cause Idiopathic Infantile Nystagmus (IIN) using the Frmd7^.tm1a and Frmd7^.tm1b murine models. We used a combination of genetic, histological and visual function techniques to characterize the role of Frmd7 gene in IIN using a novel murine model for the disease. We demonstrate that the Frmd7^.tm1b allele represents a more robust model of Frmd7 knock-out at the mRNA level. The expression of Frmd7 was investigated using both antibody staining and X-gal staining confirming previous reports that Frmd7 expression in the retina is restricted to starburst amacrine cells and demonstrating that X-gal staining recapitulates the expression pattern in this model. Thus, it offers a useful tool for further expression studies. We also show that gross retinal morphology and electrophysiology are unchanged in these Frmd7 mutant models when compared with wild-type mice. High-speed eye-tracking recordings of Frmd7 mutant mice confirm a specific horizontal optokinetic reflex defect. In summary, our study confirms the likely role for Frmd7 in the optokinetic reflex in mice mediated by starburst amacrine cells. We show that the Frmd7^.tm1b model provides a more robust knock-out than the Frmd7^.tm1a model at the mRNA level, although the functional consequence is unchanged. Finally, we establish a robust eye-tracking technique in mice that can be used in a variety of future studies using this model and others. Although our data highlight a deficit in the optiokinetic reflex as a result of the starburst amacrine cells in the retina, this does not rule out the involvement of other cells, in the brain or the retina where Frmd7 is expressed, in the pathophysiology of IIN.

An Intraocular Pressure Polygenic Risk Score Stratifies Multiple Primary Open-Angle Glaucoma Parameters Including Treatment Intensity

PURPOSE

To examine the combined effects of common genetic variants associated with intraocular pressure (IOP) on primary open-angle glaucoma (POAG) phenotype using a polygenic risk score (PRS) stratification.

DESIGN

Cross-sectional study.

PARTICIPANTS

For the primary analysis, we examined the glaucoma phenotype of 2154 POAG patients enrolled in the Australian and New Zealand Registry of Advanced Glaucoma, including patients recruited from the United Kingdom. For replication, we examined an independent cohort of 624 early POAG patients.

METHODS

Using IOP genome-wide association study summary statistics, we developed a PRS derived solely from IOP-associated variants and stratified POAG patients into 3 risk tiers. The lowest and highest quintiles of the score were set as the low- and high-risk groups, respectively, and the other quintiles were set as the intermediate risk group.

MAIN OUTCOME MEASURES

Clinical glaucoma phenotype including maximum recorded IOP, age at diagnosis, number of family members affected by glaucoma, cup-to-disc ratio, visual field mean deviation, and treatment intensity.

RESULTS

A dose-response relationship was found between the IOP PRS and the maximum recorded IOP, with the high genetic risk group having a higher maximum IOP by 1.7 mmHg (standard deviation [SD], 0.62 mmHg) than the low genetic risk group (P = 0.006). Compared with the low genetic risk group, the high genetic risk group had a younger age of diagnosis by 3.7 years (SD, 1.0 years; P < 0.001), more family members affected by 0.46 members (SD, 0.11 members; P < 0.001), and higher rates of incisional surgery (odds ratio, 1.5; 95% confidence interval, 1.1-2.0; P = 0.007). No statistically significant difference was found in mean deviation. We further replicated the maximum IOP, number of family members affected by glaucoma, and treatment intensity (number of medications) results in the early POAG cohort (P ≤ 0.01).

CONCLUSIONS

The IOP PRS was correlated positively with maximum IOP, disease severity, need for surgery, and number of affected family members. Genes acting via IOP-mediated pathways, when considered in aggregate, have clinically important and reproducible implications for glaucoma patients and their close family members.

Publisher Correction: Protein-altering variants associated with body mass index implicate pathways that control energy intake and expenditure in obesity

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Comprehensive sequencing of the myocilin gene in a selected cohort of severe primary open-angle glaucoma patients

Primary open-angle glaucoma (POAG) is the most common form of glaucoma, prevalent in approximately 1–2% of Caucasians in the UK over the age of 40. It is characterised by an open anterior chamber angle, raised intraocular pressure (IOP) and optic nerve damage leading to loss of sight. The myocilin gene (MYOC) is the most common glaucoma-causing gene, accounting for ~2% of British POAG cases. 358 patients were selected for next generation sequencing (NGS) with the following selection criteria: Caucasian ethnicity, intraocular pressure (IOP) 21–40 mm Hg, cup:disc ratio ≥0.6 and visual field mean deviation ≤−3. The entire MYOC gene (17,321 bp) was captured including the promoter, introns, UTRs and coding exons. We identify 12 exonic variants (one stop-gain, five missense and six synonymous variants), two promoter variants, 133 intronic variants, two 3′ UTR variants and 23 intergenic variants. Four known or predicted pathogenic exonic variants (p.R126W, p.K216K, p.Q368* and p.T419A) were identified across 11 patients, which accounts for 3.07% of this POAG cohort. This is the first time that the entire region of MYOC has been sequenced and variants reported for a cohort of POAG patients.

Association of Genetic Variants With Response to Anti-Vascular Endothelial Growth Factor Therapy in Age-Related Macular Degeneration

Importance

Visual acuity (VA) outcomes differ considerably among patients with neovascular age-related macular degeneration (nAMD) treated with anti-vascular endothelial growth factor (VEGF) drugs. Identification of pharmacogenetic associations may help clinicians understand the mechanisms underlying this variability as well as pave the way for personalized treatment in nAMD.

Objective

To identify genetic factors associated with variability in the response to anti-VEGF therapy for patients with nAMD.

Design, Setting, and Participants

In this multicenter genome-wide association study, 678 patients with nAMD with genome-wide genotyping data were included in the discovery phase; 1380 additional patients with nAMD were genotyped for selected common variants in the replication phase. All participants received 3 monthly injections of bevacizumab or ranibizumab. Clinical data were evaluated for inclusion/exclusion criteria from October 2014 to October 2015, followed by data analysis from October 2015 to February 2016. For replication cohort genotyping, clinical data collection and analysis (including meta-analysis) was performed from March 2016 to April 2017.

Main Outcomes and Measures

Change in VA after the loading dose of 3 monthly anti-VEGF injections compared with baseline.

Results

Of the 2058 included patients, 1210 (58.8%) were women, and the mean (SD) age across all cohorts was 78 (7.4) years. Patients included in the discovery cohort and most of the patients in the replication cohorts were of European descent. The mean (SD) baseline VA was 51.3 (20.3) Early Treatment Diabetic Retinopathy Study (ETDRS) score letters, and the mean (SD) change in VA after the loading dose of 3 monthly injections was a gain of 5.1 (13.9) ETDRS score letters (ie, 1-line gain). Genome-wide single-variant analyses of common variants revealed 5 independent loci that reached a P value less than 10 × 10-5. After replication and meta-analysis of the lead variants, rs12138564 located in the CCT3 gene remained nominally associated with a better treatment outcome (ETDRS letter gain, 1.7; β, 0.034; SE, 0.008; P = 1.38 × 10-5). Genome-wide gene-based optimal unified sequence kernel association test of rare variants showed genome-wide significant associations for the C10orf88 (P = 4.22 × 10-7) and UNC93B1 (P = 6.09 × 10-7) genes, in both cases leading to a worse treatment outcome. Patients carrying rare variants in the C10orf88 and UNC93B1 genes lost a mean (SD) VA of 30.6 (17.4) ETDRS score letters (ie, loss of 6.09 lines) and 26.5 (13.8) ETDRS score letters (ie, loss of 5.29 lines), respectively, after 3 months of anti-VEGF treatment.

Conclusions and Relevance

We propose that there is a limited contribution of common genetic variants to variability in nAMD treatment response. Our results suggest that rare protein-altering variants in the C10orf88 and UNC93B1 genes are associated with a worse response to anti-VEGF therapy in patients with nAMD, but these results require further validation in other cohorts.

Publisher Correction: Protein-altering variants associated with body mass index implicate pathways that control energy intake and expenditure in obesity

In the version of this article originally published, one of the two authors with the name Wei Zhao was omitted from the author list and the affiliations for both authors were assigned to the single Wei Zhao in the author list. In addition, the ORCID for Wei Zhao (Department of Biostatistics and Epidemiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA) was incorrectly assigned to author Wei Zhou. The errors have been corrected in the HTML and PDF versions of the article.

Publisher Correction: Protein-altering variants associated with body mass index implicate pathways that control energy intake and expenditure in obesity

In the published version of this paper, the name of author Emanuele Di Angelantonio was misspelled. This error has now been corrected in the HTML and PDF versions of the article.

Protein-altering variants associated with body mass index implicate pathways that control energy intake and expenditure in obesity

Genome-wide association studies (GWAS) have identified >250 loci for body mass index (BMI), implicating pathways related to neuronal biology. Most GWAS loci represent clusters of common, noncoding variants from which pinpointing causal genes remains challenging. Here we combined data from 718,734 individuals to discover rare and low-frequency (minor allele frequency (MAF) < 5%) coding variants associated with BMI. We identified 14 coding variants in 13 genes, of which 8 variants were in genes (ZBTB7B, ACHE, RAPGEF3, RAB21, ZFHX3, ENTPD6, ZFR2 and ZNF169) newly implicated in human obesity, 2 variants were in genes (MC4R and KSR2) previously observed to be mutated in extreme obesity and 2 variants were in GIPR. The effect sizes of rare variants are ~10 times larger than those of common variants, with the largest effect observed in carriers of an MC4R mutation introducing a stop codon (p.Tyr35Ter, MAF = 0.01%), who weighed ~7 kg more than non-carriers. Pathway analyses based on the variants associated with BMI confirm enrichment of neuronal genes and provide new evidence for adipocyte and energy expenditure biology, widening the potential of genetically supported therapeutic targets in obesity.

Complement factor H genetic variant and age-related macular degeneration: effect size, modifiers and relationship to disease subtype

BACKGROUND

Variation in the complement factor H gene (CFH) is associated with risk of late age-related macular degeneration (AMD). Previous studies have been case-control studies in populations of European ancestry with little differentiation in AMD subtype, and insufficient power to confirm or refute effect modification by smoking.

METHODS

To precisely quantify the association of the single nucleotide polymorphism (SNP rs1061170, 'Y402H') with risk of AMD among studies with differing study designs, participant ancestry and AMD grade and to investigate effect modification by smoking, we report two unpublished genetic association studies (n = 2759) combined with data from 24 published studies (26 studies, 26,494 individuals, including 14,174 cases of AMD) of European ancestry, 10 of which provided individual-level data used to test gene-smoking interaction; and 16 published studies from non-European ancestry.

RESULTS

In individuals of European ancestry, there was a significant association between Y402H and late-AMD with a per-allele odds ratio (OR) of 2.27 [95% confidence interval (CI) 2.10-2.45; P = 1.1 x 10(-161)]. There was no evidence of effect modification by smoking (P = 0.75). The frequency of Y402H varied by ancestral origin and the association with AMD in non-Europeans was less clear, limited by paucity of studies.

CONCLUSION

The Y402H variant confers a 2-fold higher risk of late-AMD per copy in individuals of European descent. This was stable to stratification by study design and AMD classification and not modified by smoking. The lack of association in non-Europeans requires further verification. These findings are of direct relevance for disease prediction. New research is needed to ascertain if differences in circulating levels, expression or activity of factor H protein explain the genetic association.

Relationship between MRI and clinical findings in the acromioclavicular joint

OBJECTIVE

To determine the relationship between the magnetic resonance (MR) appearance of the acromioclavicular (AC) joint and the physical findings.

DESIGN

A total of 116 consecutive patients underwent routine MR imaging (MRI) of the shoulder over an 18-month period. All MR studies were interpreted by a blinded, experienced musculoskeletal radiologist. Eleven variables were studied: the presence of osteophytes; fluid in the joint; fluid outside the joint; high signal in the clavicle or in the acromion; fluid in the subacromial bursa; irregularity of the joint margins; bulging of the capsule; widening of the joint; the age of the patient; and the presence of a rotator cuff tear. The clinical information was supplied by an experienced shoulder surgeon blinded to the MRI findings. A control group of 23 normal volunteers was also studied.

RESULTS

The only statistically significant correlation ( P=0.0249) was between high signal in the distal clavicle and degenerative changes found clinically. A weaker relationship existed between fluid in the joint and the clinical examination and between increasing degenerative changes and advancing age. Otherwise, no material relationship was found between any of the other MR abnormalities and the clinical picture.

CONCLUSION

There appears to be no real correlation between the MR appearances and the clinical findings in the AC joint.

Memory dysfunction in multiple sclerosis corresponds to juxtacortical lesion load on fast fluid-attenuated inversion-recovery MR images

BACKGROUND AND PURPOSE

MR imaging is a sensitive diagnostic tool and paraclinical marker of disease activity and prognosis in multiple sclerosis (MS), yet the role of MR imaging of MS is controversial. The aim of this study was to describe the relationship between cognitive function and MS lesion size and position, as shown on comparative images from conventional spin-echo (CSE) and fast fluid-attenuated inversion-recovery (fast FLAIR) MR studies.

METHODS

CSE and fast FLAIR sequences consisted of 40 noncontiguous, 3-mm-thick axial sections matched for geometric position in 18 patients with relapsing-remitting MS. Lesions were scored for size, anatomic position, and their comparative appearance on CSE and fast FLAIR images. The neuropsychological assessment tested general psychological performance, memory, and frontal lobe executive function.

RESULTS

Fast FLAIR images showed significantly more small (146 versus six) and medium-sized (18 versus four) juxtacortical lesions than did CSE sequences. Small juxtacortical lesions displayed only on fast FLAIR images had a distinctive appearance, suggestive of small areas of perivascular inflammation. The number of these lesions corresponded to reduced performance on the fifth and delayed trials of the Rey Auditory Verbal Learning memory function test.

CONCLUSION

Fast FLAIR images show small lesions at the juxtacortical boundary that are not seen on CSE studies. The presence of such lesions correlates with impaired retention of information in memory tasks, which is characteristic of cognitive problems in patients with MS.

Awareness of involuntary movements in Huntington disease

OBJECTIVE

To determine why patients with Huntington disease are apparently unaware of their involuntary movements.

DESIGN

Correlative study using a subjective report questionnaire of physical symptoms and objective measures of neurologic and cognitive dysfunction.

PATIENTS

Forty patients with Huntington disease attending a regional Huntington disease clinic.

RESULTS

Patients were poor at reporting experiential symptoms of involuntary movements. There was no relationship between self-report of these symptoms and objective indices of motor dysfunction or severity of cognitive impairment. Patients could, however, report secondary consequences of their movement disorder, which correlated highly with nonchoreic indices of motor dysfunction.

CONCLUSIONS

Patients with Huntington disease have impaired subjective experience of chorea. Denial of symptoms is likely to have a physiological basis and is not a secondary consequence of patients' cognitive impairment or a psychological defense against a debilitating disease.

The glycosylation of red cell autoantibodies affects their functional activity in vitro

Factors governing the functional activity of red cell autoantibodies are poorly defined. Here we report the presence of qualitative differences in the glycosylation of IgG autoantibodies which affect in vitro interactions with Fc gamma RIII. The following antibodies were affinity-purified by adsorption and elution from normal red cells: IgG eluted from the red cells of 27 haemolysing or non-haemolysing patients, anti-D in sera from 11 pregnant women, and IgG1 and IgG3 human monoclonal anti-D. Monoclonal antibodies with differing levels of agalactosyl IgG were produced by culturing cell lines at high or low cell density. The % IgG with oligosaccharides lacking terminal galactose residues (agalactosyl IgG) of antibodies was designated as low, medium or high according to their reactivity with a monoclonal antibody to terminal N-acetylglucosamine. Fc gamma RIII-mediated functional activity was assessed by measuring the K-cell-mediated lysis of red cells in eluates diluted to achieve comparable levels of red cells sensitization. All eluates containing allo-anti-D were lytic (range 74-100%). In contrast, lysis by autoantibodies varied from 0 to 100%; 11/13 eluates from red cells of haemolysing patients promoted > 5% lysis compared to 2/7 eluates from red cells of non-haemolysing patients (P < 0.02). The ability of autoantibodies to promote K-cell-mediated red cell lysis correlated inversely with their level of agalactosyl IgG (r = -0.56, P < 0.01, n = 23). Further, monoclonal anti-D antibodies with very low levels of agalactosyl IgG were comparatively more lytic than the same antibodies containing more agalactosyl IgG. Analysis of the ratio of kappa:lambda light chains suggested that autoantibodies from 6/19 patients were monoclonal or oligoclonal in nature. The data indicate that IgG red cell autoantibodies from different patients are functionally heterogenous, and that this may be due, at least in part, to qualitative differences in the Fc region glycosylation reflected by differences in the proportion of agalactosyl IgG. This heterogeneity is consistent with the clonally-restricted nature of the autoantibodies in some patients.

Autobiographical experience and word meaning

The role of current personal experience in understanding of word meaning was investigated in a patient, WM, who suffers from semantic dementia. The study was prompted by the observation that WM, despite being severely impaired on formal tests of word comprehension and naming, retained a range of vocabulary pertaining to her daily life. If autobiographical experience has a general facilitatory effect, then this should affect which concepts are retained and which lost, but not influence the quality of that conceptual knowledge. Conversely, if personal autobiography has a direct role in investing concepts with meaning, then WM's understanding of nominal terms that she uses spontaneously in conversation ought not to be normal, but should be constrained by the autobiographical context in which she uses those terms. WM could define nouns and noun phrases drawn from her conversational vocabulary, but her definitions had a markedly autobiographical quality. Moreover, WM was extremely impaired in her ability to define new noun phrases, constructed by combining words from her conversational vocabulary (e.g. "dog licence", constructed from "driving licence" and "dog"; "oil field" constructed from "oil" and "field"). It was concluded that WM does not have normal conceptual understanding of nouns and noun phrases that she uses appropriately in conversation. Her understanding is narrow and autobiographically constrained. The findings, which suggest an interactive relationship between autobiographical and semantic memory, have implications for understanding of the progressive breakdown of semantic knowledge.

The functional activity of human monocytes passively sensitized with monoclonal anti-D suggests a novel role for Fc gamma RI in the immune destruction of blood cells

The role of Fc gamma RI in the immune destruction of blood cells is uncertain as serum IgG levels are sufficient to competitively inhibit interactions between this high-affinity receptor and sensitized red cells. In the current study, it is proposed that, rather than functioning as a receptor for opsonized red cells, Fc gamma RI might, under appropriate conditions, mediate the passive sensitization (or 'arming') of human macrophages with IgG antibodies resulting in the in vivo destruction of unsensitized cells expressing the corresponding antigen. To examine this hypothesis, Fc gamma RI-bearing human monocytes and U937 cells were first passively sensitized by incubation in vitro with human monoclonal anti-D, and then incubated with D-positive red cells. The uptake of monoclonal anti-D by U937 cells was rapid and, in the presence of 2.5 micrograms/ml IgG1 or IgG3 anti-D, was almost complete after 5 min at 37 degrees. Subsequent incubation of passively sensitized U937 cells in an IgG-free medium for 1 hr at 37 degrees resulted in the loss from the cell surface of approximately 50% cell-bound IgG; the remaining cell-bound IgG was lost more slowly despite repeated washing. In functional assays, passively sensitized monocytes (M-IgG) mediated adherent, phagocytic and chemiluminescent (CL) responses to D-positive red cells. After incubation of M-IgG in 50% v/v fresh normal human serum (FNHS) for 2 hr, sufficient anti-D remained bound to monocytes to promote the adherence of red cells. The adherence and phagocytosis of red cells by M-IgG was enhanced by the simultaneous addition of 50% FNHS, probably owing to the binding of low levels of C3bi to red cells. In contrast, phagocytic and CL responses of unsensitized monocytes to anti-D-sensitized red cells (E-IgG) were abrogated in the presence of 0.25% v/v FNHS, presumably owing to blocking of Fc gamma RI by IgG. It is considered that in vivo, Fc gamma RI may mediate the passive sensitization of macrophages in close proximity with antibody-secreting cells in the reticular network of the splenic cords. Once 'armed' in this way, macrophages may destroy cells expressing the appropriate antigen.