Leber congenital amaurosis as the initial and essential manifestation in a Chinese patient with autoimmune polyglandular syndrome Type 1.

PURPOSE: Autoimmune polyglandular syndrome Type 1 (APS-1) is a rare autosomal recessive disorder caused by defects in the autoimmune regulator (AIRE) gene. Patients are generally diagnosed at ages between five and fifteen years when they exhibit three or more manifestations, most typically mucocutaneous candidiasis, autoimmune Addison's disease, and hypoparathyroidism. Our study aims to report the first case of a Chinese APS-1 patient, presented with LCA as the initial and essential clinical feature of this rare syndrome. METHODS: Detailed medical and family history were recorded for the patient. Also, the comprehensive ophthalmological examinations were conducted. Whole exome sequencing (WES) was applied to screen pathogenic variants. Sanger sequencing validation and segregation analysis were further performed for confirmation. RESULTS: A 3-year-old boy with severely impaired vision and initially referred as LCA. However, with a detailed history review, oral candidiasis, dental enamel hypoplasia, and nail candida infection were revealed. Moreover, genetic analysis revealed the homozygous c.769C>T (p.R257X) in AIRE gene (NM_000383.3) as the causative variant. CONCLUSION: We presented one case diagnosed with APS-1 based on clinical characteristics and genetic analysis. Our study demonstrated that LCA could serve as a warning sign for APS-1 and a potential trigger of early screening, which might prevent life-threatening complications.

An Alu-mediated duplication in NMNAT1, involved in NAD biosynthesis, causes a novel syndrome, SHILCA, affecting multiple tissues and organs.

We investigated the genetic origin of the phenotype displayed by three children from two unrelated Italian families, presenting with a previously unrecognized autosomal recessive disorder that included a severe form of spondylo-epiphyseal dysplasia, sensorineural hearing loss, intellectual disability and Leber congenital amaurosis (SHILCA), as well as some brain anomalies that were visible at the MRI. Autozygome-based analysis showed that these children shared a 4.76 Mb region of homozygosity on chromosome 1, with an identical haplotype. Nonetheless, whole-exome sequencing failed to identify any shared rare coding variants, in this region or elsewhere. We then determined the transcriptome of patients' fibroblasts by RNA sequencing, followed by additional whole-genome sequencing experiments. Gene expression analysis revealed a 4-fold downregulation of the gene NMNAT1, residing indeed in the shared autozygous interval. Short- and long-read whole-genome sequencing highlighted a duplication involving 2 out of the 5 exons of NMNAT1 main isoform (NM_022787.3), leading to the production of aberrant mRNAs. Pathogenic variants in NMNAT1 have been previously shown to cause non-syndromic Leber congenital amaurosis (LCA). However, no patient with null biallelic mutations has ever been described, and murine Nmnat1 knockouts show embryonic lethality, indicating that complete absence of NMNAT1 activity is probably not compatible with life. The rearrangement found in our cases, presumably causing a strong but not complete reduction of enzymatic activity, may therefore result in an intermediate syndromic phenotype with respect to LCA and lethality.

Intraperitoneal chromophore injections delay early-onset and rapid retinal cone degeneration in a mouse model of Leber congenital amaurosis.

Highly expressed in the retinal pigment epithelium (RPE), the RPE-specific 65-kDa (RPE65) enzyme is indispensable to generate 11-cis-retinal (11cRAL), a chromophore for rhodopsin and cone photopigments. RPE65 deficiency can lead to Leber congenital amaurosis type 2 (LCA2), in which the isomerization of photobleached all-trans-retinal into photosensitive 11cRAL is blocked, ultimately causing severe retinal dysfunction and degeneration. The related mouse models, which are constructed through gene knockout or caused by spontaneous mutations, morphologically present with early-onset and rapid retinal cone cells degeneration, including loss of short-wavelength-sensitive cone opsins (S-opsins) and mislocalization of medium-wavelength-sensitive cone opsins (M-opsins). Studies have shown that routine Rpe65 gene replacement therapy, mediated by an adeno-associated virus (AAV) vector, can restore RPE65 protein. However, AAV transfection and Rpe65 transgene expression require at least one to two weeks, and the treatment cannot fully block the early-onset cone degeneration. To determine the feasibility of delaying cone degeneration before gene therapy, we investigated the impact of 11cRAL treatment in an early-age LCA2 retinal degeneration 12 (rd12) mouse model. Similar to human patients, the mouse model carries a spontaneous mutation in the Rpe65 gene, which results in disrupted endogenous 11cRAL regeneration. We found that RPE65 deficiency did not notably affect rodent retinal vessels. Under red light illumination, the rd12 mice were intraperitoneally injected with exogenous 11cRAL from postnatal day (P) 14 to P21. Three days after the last injection, a notable recovery of retinal function was observed using scotopic and photopic electroretinograms. Using optical coherence tomography and histological analyses of the deficient retinas, we found changes in the thickness of the photoreceptor outer segment (OS); this change could be rescued by early 11cRAL treatment. In addition, the treatment notably preserved M- and S-opsins, both of which maintained appropriate localization inside cone cells, as shown by the wild-type mice. In contrast, the age-matched untreated rd12 mice were characterized by retinal S-opsin loss and M-opsin mislocalization from the photoreceptor OS to the inner segment, outer nuclear layer, or outer plexiform layer. Notably, 11cRAL treatment could not maintain retinal function for a long time. Ten days after the last injection, the rod and M-cone electroretinograms significantly decreased, and S-cone responses almost extinguished. Our findings suggest that early 11cRAL treatment is useful for restoring retinal function and rescuing morphology in the rd12 mouse model, and the early-onset and rapid cone degeneration can be delayed before gene therapy.

LEBER CONGENITAL AMAUROSIS DUE TO CEP290 MUTATIONS-SEVERE VISION IMPAIRMENT WITH A HIGH UNMET MEDICAL NEED: A Review.

PURPOSE: Leber congenital amaurosis due to CEP290 mutations (LCA10) is an inherited retinal disease that often results in severe visual impairment or blindness in early childhood. Currently, there are no approved treatments, highlighting the considerable unmet medical need associated with LCA10. We aimed to review the clinical characteristics of LCA10, its impact on patients and society, and the investigational treatment strategies currently in development. METHODS: Review of the current literature. RESULTS: LCA10 is an autosomal recessive ciliopathy, for which the CEP290 intronic variant c.2991+1655A>G (p.Cys998X) is the most common mutation. Usually diagnosed in early childhood, most patients with LCA10 have severe visual impairment during their first decade of life, which significantly affects the quality of life and development. LCA10 also has a significant societal burden (direct and indirect costs). RNA editing using antisense oligonucleotides or Staphylococcus aureus CRISPR-associated protein-9 nuclease is currently under investigation for treatment of p.Cys998X LCA10. Specifically, the antisense oligonucleotide therapy QR-110 (sepofarsen) has demonstrated encouraging safety and efficacy data in a first-in-human trial; a phase 3 clinical trial is ongoing. CONCLUSION: Interventions that can preserve or improve vision in patients with LCA10 have considerable potential to improve the patient quality of life and reduce burden of disease.

New Insights on the Genetic Basis Underlying SHILCA Syndrome: Characterization of the NMNAT1 Pathological Alterations Due to Compound Heterozygous Mutations and Identification of a Novel Alternative Isoform.

This study aims to genetically characterize a two-year-old patient suffering from multiple systemic abnormalities, including skeletal, nervous and developmental involvements and Leber congenital amaurosis (LCA). Genetic screening by next-generation sequencing identified two heterozygous pathogenic variants in nicotinamide mononucleotide adenylyltransferase 1 (NMNAT1) as the molecular cause of the disease: c.439+5G>T and c.299+526_*968dup.This splice variant has never been reported to date, whereas pathogenic duplication has recently been associated with cases displaying an autosomal recessive disorder that includes a severe form of spondylo-epiphyseal dysplasia, sensorineural hearing loss, intellectual disability and LCA (SHILCA), as well as some brain anomalies. Our patient presented clinical manifestations which correlated strongly with this reported syndrome. To further study the possible transcriptional alterations resulting from these mutations, mRNA expression assays were performed in the patient and her father. The obtained results detected aberrant alternative transcripts and unbalanced levels of expression, consistent with severe systemic involvement. Moreover, these analyses also detected a novel NMNAT1 isoform, which is variably expressed in healthy human tissues. Altogether, these findings represent new evidence of the correlation of NMNAT1 and SHILCA syndrome, and provide additional insights into the healthy and pathogenic expression of this gene.

Threatening drug-drug interaction in a kidney transplant patient with coronavirus disease 2019 (COVID-19).

During the novel coronavirus pandemic, organ transplant recipients represent a frail susceptible category due to long-term immunosuppressive therapy. For this reason, clinical manifestations may differ from general population and different treatment approaches may be needed. We present the case of a 36-year-old kidney-transplanted woman affected by Senior-Loken syndrome diagnosed with COVID-19 pneumonia after a contact with her positive mother. Initial symptoms were fatigue, dry cough, and coryza; she never had fever nor oxygen supplementation. Hydroxychloroquine and lopinavir/ritonavir were started, and the antiviral drug was replaced with darunavir/cobicistat after 2 days for diarrhea. Immunosuppressant levels were closely monitored, and we observed very high tacrolimus trough levels despite initial dose reduction. The patient was left with steroid therapy alone. The peculiarity of clinical presentation and the management difficulties represent the flagship of our case report. We stress the need for guidelines in transplant recipients with COVID-19 infection with particular regard to the management of therapy.

In vivo phenotypic and molecular characterization of retinal degeneration in mouse models of three ciliopathies.

Cilia are highly conserved and ubiquitously expressed organelles. Ciliary defects of genetic origins lead to ciliopathies, in which retinal degeneration (RD) is one cardinal clinical feature. In order to efficiently find and design new therapeutic strategies the underlying mechanism of retinal degeneration of three murine model was compared. The rodent models correspond to three emblematic ciliopathies, namely: Bardet-Biedl Syndrome (BBS), Alström Syndrome (ALMS) and CEP290-mediated Leber Congenital Amaurosis (LCA). Scotopic rodent electroretinography (ERG) was used to test the retinal function of mice, Transmitted Electron microscopy (T.E.M) was performed to assess retinal structural defects and real-time PCR for targeted genes was used to monitor the expression levels of the major apoptotic Caspase-related pathways in retinal extracts to identify pathological pathways driving the RD in order to identify potential therapeutic targets. We found that BBS and CEP290-mediated LCA mouse models exhibit perinatal retinal degeneration associated with rhodopsin mislocalization in the photoreceptor and the induction of an Endoplasmic Reticulum (ER) stress. On the other hand, the tested ALMS mouse model, displayed a slower degeneration phenotype, with no Rhodopsin mislocalization nor ER-stress activity. Our data points out that behind the general phenotype of vision loss associated with these ciliopathies, the mechanisms and kinetics of disease progression are different.

Suppressing thyroid hormone signaling preserves cone photoreceptors in mouse models of retinal degeneration.

Cone phototransduction and survival of cones in the human macula is essential for color vision and for visual acuity. Progressive cone degeneration in age-related macular degeneration, Stargardt disease, and recessive cone dystrophies is a major cause of blindness. Thyroid hormone (TH) signaling, which regulates cell proliferation, differentiation, and apoptosis, plays a central role in cone opsin expression and patterning in the retina. Here, we investigated whether TH signaling affects cone viability in inherited retinal degeneration mouse models. Retinol isomerase RPE65-deficient mice [a model of Leber congenital amaurosis (LCA) with rapid cone loss] and cone photoreceptor function loss type 1 mice (severe recessive achromatopsia) were used to determine whether suppressing TH signaling with antithyroid treatment reduces cone death. Further, cone cyclic nucleotide-gated channel B subunit-deficient mice (moderate achromatopsia) and guanylate cyclase 2e-deficient mice (LCA with slower cone loss) were used to determine whether triiodothyronine (T3) treatment (stimulating TH signaling) causes deterioration of cones. We found that cone density in retinol isomerase RPE65-deficient and cone photoreceptor function loss type 1 mice increased about sixfold following antithyroid treatment. Cone density in cone cyclic nucleotide-gated channel B subunit-deficient and guanylate cyclase 2e-deficient mice decreased about 40% following T3 treatment. The effect of TH signaling on cone viability appears to be independent of its regulation on cone opsin expression. This work demonstrates that suppressing TH signaling in retina dystrophy mouse models is protective of cones, providing insights into cone preservation and therapeutic interventions.

Gene therapy using self-complementary Y733F capsid mutant AAV2/8 restores vision in a model of early onset Leber congenital amaurosis.

Defects in the photoreceptor-specific gene aryl hydrocarbon receptor interacting protein-like 1 (Aipl1) are associated with Leber congenital amaurosis (LCA), a childhood blinding disease with early-onset retinal degeneration and vision loss. Furthermore, Aipl1 defects are characterized at the most severe end of the LCA spectrum. The rapid photoreceptor degeneration and vision loss observed in the LCA patient population are mimicked in a mouse model lacking AIPL1. Using this model, we evaluated if gene replacement therapy using recent advancements in adeno-associated viral vectors (AAV) provides advantages in preventing rapid retinal degeneration. Specifically, we demonstrated that the novel self-complementary Y733F capsid mutant AAV2/8 (sc-Y733F-AAV) provided greater preservation of photoreceptors and functional vision in Aipl1 null mice compared with single-stranded AAV2/8. The benefits of sc-Y733F-AAV were evident following viral administration during the active phase of retinal degeneration, where only sc-Y733F-AAV treatment achieved functional vision rescue. This result was likely due to higher and earlier onset of Aipl1 expression. Based on our studies, we conclude that the sc-Y733F-AAV2/8 viral vector, to date, achieves the best rescue for rapid retinal degeneration in Aipl1 null mice. Our results provide important considerations for viral vectors to be used in future gene therapy clinical trials targeting a wider severity spectrum of inherited retinal dystrophies.

Dual phenotype: co-occurring Leber congenital amaurosis and familial exudative vitreoretinopathy: a case report.

PURPOSE: To report the concurrent presentation and management of IQCB1-associated Leber Congenital Amaurosis and NDP-associated Familial Exudative Vitreoretinopathy (FEVR). MATERIALS AND METHODS: A 6-month-old Caucasian infant presented with poor visual response, high hypermetropia, and infantile-nystagmus with a provisional diagnosis of Leber Congenital Amaurosis based on clinical findings. Genetic counseling and testing were performed with a 285 gene retinal dystrophy panel (Blueprint Genetics). Clinical characteristics, presentation, ancillary testing results, and management are described. RESULTS: Two previously reported heterozygous pathogenic variants in ICQB1 were identified (c.1518_1519del (p.His506Glnfs*13) and c.1381C>T, p.Arg461*) segregating in trans. In addition, a variation of uncertain significance (VUS) was found in NDP (c.280C>T; p.His94Tyr). Fluorescein angiography was performed demonstrating peripheral avascularity and retinal telangiectasia without frank neovascularization. Peripheral ablative laser was applied to the avascular zone. CONCLUSIONS: The NDP VUS likely represents a pathogenic variant given the FEVR phenotype in addition to retinal degeneration, creating a rare dual phenotype. The combination of low oxygen demand from the IQCB1-associated retinal degeneration and NDP variant may have led to a more attenuated FEVR presentation with uncertain prognosis. A molecular diagnosis informed ocular and renal surveillance, as well as the recurrence risk for future offspring.

Perifoveal Chorioretinal Atrophy after Subretinal Voretigene Neparvovec-rzyl for RPE65-Mediated Leber Congenital Amaurosis.

PURPOSE: To report an anatomic change following subretinal injection of voretigene neparvovec-rzyl (VN) for RPE65-mediated Leber congenital amaurosis. DESIGN: Multicenter, retrospective chart review. PARTICIPANTS: Patients who underwent subretinal VN injection at each of 4 participating institutions. METHODS: Patients were identified as having perifoveal chorioretinal atrophy if (1) the areas of atrophy were not directly related to the touch-down site of the subretinal cannula; and (2) the area of atrophy progressively enlarged over time. Demographic data, visual acuity, refractive error, fundus photographs, OCT, visual fields, and full-field stimulus threshold (FST) were analyzed. MAIN OUTCOME MEASURES: Outcome measures included change in visual acuity, FST, visual fields, and location of atrophy relative to subretinal bleb position. RESULTS: A total of 18 eyes of 10 patients who underwent subretinal injection of VN were identified as having developed perifoveal chorioretinal atrophy. Eight of 10 patients (80%) developed bilateral atrophy. The mean age was 11.6 years (range, 5-20 years), and 6 patients (60%) were male. Baseline mean logarithm of the minimum angle of resolution visual acuity and FST were 0.82 (standard deviation [SD], 0.51) and -1.3 log cd.s/m2 (SD, 0.44), respectively. The mean spherical equivalent was -5.7 diopters (D) (range, -11.50 to +1.75 D). Atrophy was identifiable at an average of 4.7 months (SD, 4.3) after surgery and progressively enlarged in all cases up to a mean follow-up period of 11.3 months (range, 4-18 months). Atrophy developed within and outside the area of the subretinal bleb in 10 eyes (55.5%), exclusively within the area of the bleb in 7 eyes (38.9%), and exclusively outside the bleb in 1 eye (5.5%). There was no significant change in visual acuity (P = 0.45). There was a consistent improvement in FST with a mean improvement of -3.21 log cd.s/m2 (P < 0.0001). Additionally, all 13 eyes with reliable Goldmann visual fields demonstrated improvement, but 3 eyes (23.1%) demonstrated paracentral scotomas related to the atrophy. CONCLUSIONS: A subset of patients undergoing subretinal VN injection developed progressive perifoveal chorioretinal atrophy after surgery. Further study is necessary to determine what ocular, surgical delivery, and vector-related factors predispose to this complication.

Identification of a novel LCA5 mutation in a Pakistani family with Leber congenital amaurosis and cataracts.

PURPOSE: To determine the cause of Leber congenital amaurosis (LCA) and developmental cataracts in a consanguineous Pakistani family. METHODS: The diagnosis was established in all affected individuals of a Pakistani LCA family by medical history, funduscopy, and standard ERG. We performed genome-wide linkage analysis for mapping the disease locus in this family. RESULTS: Congenitally severely reduced visual acuity and nystagmus were reported for all patients who, in the later phase of the disease, also developed cataracts. LCA in the family cosegregated with homozygosity for a single nucleotide polymorphism (SNP) haplotype on chromosome 6p14.1. The respective candidate region contained Leber congenital amaurosis 5 (LCA5), a gene previously reported to underlie LCA. We subsequently identified a novel truncating mutation in exon 4 of LCA5, c.642delC, in homozygous state in all affected persons of the family. CONCLUSIONS: We report a novel LCA5 mutation causing LCA in a Pakistani family. Developmental cataracts were present in two of the four patients, raising the possibility that LCA5 mutations may predispose to this additional ocular pathology.

Senior-Løken syndrome and intracranial hypertension.

BACKGROUND: Senior-Løken syndrome (SLS) is a rare autosomal recessive disease characterised by nephronophthisis and retinal degeneration, and belongs to a group of genetically heterogeneous disorders known as the ciliopathies. MATERIALS AND METHODS: Case report of a  patient with genetically proven SLS presenting with headaches and swollen optic nerve heads, review of medical notes and ophthalmic imaging, with retinal photography, fundus autofluorescence, and OCT retinal nerve fibre layer analysis. RESULTS: We present findings in a 15 year old girl with Senior-Løken syndrome associated with compound heterozygous mutations in the SDCCAG8 gene,  who initially presented with a retinal dystrophy, and subsequent renal failure requiring renal transplantation and immunosuppression. Four and a half years later, she presented with headaches, reduced vision and clinical findings of papilloedema.  Cerebrospinal fluid analysis revealed a high opening pressure of 37cmH20 and neuroimaging was otherwise unremarkable.  Treatment with a reduced dose of oral acetazolamide resulted in symptomatic relief of headaches, and resolution of optic nerve swelling. CONCLUSION: The association of intracranial hypertension in a ciliopathy is a rare occurrence.  The aetiology of intracranial hypertension in this case is likely multi-factorial, due to renal transplantation, post-renal transplant medications and/ or weight gain.  With evidence of cilia involvement in the central nervous system, ciliary dysfunction may contribute to intracranial hypertension, and should be considered in these patients presenting with headaches. Diagnosis may be difficult with advanced retinal degeneration and baseline retinal nerve fibre layer thinning. Treatment requires careful monitoring of renal function.

GCAP neuronal calcium sensor proteins mediate photoreceptor cell death in the rd3 mouse model of LCA12 congenital blindness by involving endoplasmic reticulum stress.

Loss-of-function mutations in the retinal degeneration 3 (RD3) gene cause inherited retinopathy with impaired rod and cone function and fast retinal degeneration in patients and in the natural strain of rd3 mice. The underlying physiopathology mechanisms are not well understood. We previously proposed that guanylate cyclase-activating proteins (GCAPs) might be key Ca2+-sensors mediating the physiopathology of this disorder, based on the demonstrated toxicity of GCAP2 when blocked in its Ca2+-free form at photoreceptor inner segments. We here show that the retinal degeneration in rd3 mice is substantially delayed by GCAPs ablation. While the number of retinal photoreceptor cells is halved in 6 weeks in rd3 mice, it takes 8 months to halve in rd3/rd3 GCAPs-/- mice. Although this substantial morphological rescue does not correlate with recovery of visual function due to very diminished guanylate cyclase activity in rd3 mice, it is very informative of the mechanisms underlying photoreceptor cell death. By showing that GCAP2 is mostly in its Ca2+-free-phosphorylated state in rd3 mice, we infer that the [Ca2+]i at rod inner segments is permanently low. GCAPs are therefore retained at the inner segment in their Ca2+-free, guanylate cyclase activator state. We show that in this conformational state GCAPs induce endoplasmic reticulum (ER) stress, mitochondrial swelling, and cell death. ER stress and mitochondrial swelling are early hallmarks of rd3 retinas preceding photoreceptor cell death, that are substantially rescued by GCAPs ablation. By revealing the involvement of GCAPs-induced ER stress in the physiopathology of Leber's congenital amaurosis 12 (LCA12), this work will aid to guide novel therapies to preserve retinal integrity in LCA12 patients to expand the window for gene therapy intervention to restore vision.

Molecular Study of Nephronophthisis in 7 Unrelated Pakistani Families.

Nephronophthisis is an autosomal recessive cystic kidney disease characterized by tubular interstitial infiltration, periglomerular fibrosis, and cysts, and is the most frequent genetic cause of end-stage renal disease in children. Nephronophthisis is pleiotropic as almost all the causative genes are involved in primary cilium and centrosome function which are found in almost all human cells. Genetic heterogeneity in nephronophthisis makes the molecular and genetic diagnosis somewhat difficult. Homozygous deletions in the nephronophthisis 1 (NPHP1) gene are the major contributor of nephronophthisis cases, while other genes accounts for less than 3% each. Nephronophthisis-related ciliopathy is a term used for extrarenal symptoms in addition to nephronophthisis. Herein, we are reporting the molecular study of 7 children from independent families fulfilling the criteria of nephronophthisis. A deletion analysis of the NPHP1 gene was performed in each case, and NPHP5 mutation screening was performed in the absence of such deletion in patients with Senior Loken syndrome.

Pupillary Light Reflexes in Severe Photoreceptor Blindness Isolate the Melanopic Component of Intrinsically Photosensitive Retinal Ganglion Cells.

Purpose: Pupillary light reflex (PLR) is driven by outer retinal photoreceptors and by melanopsin-expressing intrinsically photosensitive retinal ganglion cells of the inner retina. To isolate the melanopic component, we studied patients with severe vision loss due to Leber congenital amaurosis (LCA) caused by gene mutations acting on the outer retina. Methods: Direct PLR was recorded in LCA patients (n = 21) with known molecular causation and severe vision loss. Standard stimuli (2.5 log scot-cd.m-2; ∼13 log quanta.cm-2.s-1; achromatic full-field) with 0.1- or 5-second duration were used in all patients. Additional recordings were performed with higher luminance (3.9 log scot-cd.m-2) in a subset of patients. Results: The LCA patients showed no detectable PLR to the standard stimulus with short duration. With longer-duration stimuli, a PLR was detectable in the majority (18/21) of patients. The latency of the PLR was 2.8 ± 1.3 seconds, whereas normal latency was 0.19 ± 0.02 seconds. Peak contraction amplitude in patients was 1.1 ± 0.9 mm at 6.2 ± 2.3 seconds, considerably different from normal amplitude of 4.2 ± 0.4 mm at 3.0 ± 0.4 seconds. Recordings with higher luminance demonstrated that PLRs in severe LCA could also be evoked with short-duration stimuli. Conclusions: The PLR in severe LCA patients likely represents the activation of the melanopic circuit in isolation from rod and cone input. Knowledge of the properties of the human melanopic PLR allows not only comparison to those in animal models but also serves to define the fidelity of postretinal transmission in clinical trials targeting patients with no outer retinal function.

The clinical evaluation of infantile nystagmus: What to do first and why.

INTRODUCTION: Infantile nystagmus has many causes, some life threatening. We determined the most common diagnoses in order to develop a testing algorithm. METHODS: Retrospective chart review. Exclusion criteria were no nystagmus, acquired after 6 months, or lack of examination. DATA COLLECTED: pediatric eye examination findings, ancillary testing, order of testing, referral, and final diagnoses. Final diagnosis was defined as meeting published clinical criteria and/or confirmed by diagnostic testing. Patients with a diagnosis not meeting the definition were "unknown." Patients with incomplete testing were "incomplete." Patients with multiple plausible etiologies were "multifactorial." Patients with negative complete workup were "motor." RESULTS: A total of 284 charts were identified; 202 met inclusion criteria. The three most common causes were Albinism (19%), Leber Congenital Amaurosis (LCA; 14%), and Non-LCA retinal dystrophy (13%). Anatomic retinal disorders comprised 10%, motor another 10%. The most common first test was MRI (74/202) with a diagnostic yield of 16%. For 28 MRI-first patients, nystagmus alone was the indication; for 46 MRI-first patients other neurologic signs were present. 0/28 nystagmus-only patients had a diagnostic MRI while 14/46 (30%) with neurologic signs did. The yield of ERG as first test was 56%, OCT 55%, and molecular genetic testing 47%. Overall, 90% of patients had an etiology identified. CONCLUSION: The most common causes of infantile nystagmus were retinal disorders (56%), however the most common first test was brain MRI. For patients without other neurologic stigmata complete pediatric eye examination, ERG, OCT, and molecular genetic testing had a higher yield than MRI scan. If MRI is not diagnostic, a complete ophthalmologic workup should be pursued.

LEBER CONGENITAL AMAUROSIS WITH LARGE RETINAL PIGMENT CLUMPS CAUSED BY COMPOUND HETEROZYGOUS MUTATIONS IN KCNJ13.

PURPOSE: To describe a patient with mutations in KCNJ13 presenting particular clinical features. METHODS: Standard ophthalmic examination, fundus autofluorescence, spectral domain optical coherence tomography, full-field electroretinography. The 3 exons of KCNJ13 were polymerase chain reaction amplified and Sanger sequenced. PATIENTS: A 31-year-old man with Leber congenital amaurosis. RESULTS: Patient had nystagmus since childhood, best-corrected visual acuity limited to 20/400 OD and 20/200 OS, and had cataracts extracted in both eyes. There were clumpy pigment deposits mostly in macular area, causing an uneven line of retinal pigment epithelium on spectral domain optical coherence tomography. In retinal parts devoid of pigment deposits around the optic disk and in periphery, retinal thickness was increased and hyperreflective formations were present either in the inner nuclear layer or in the outer nuclear layer. The patient was compound heterozygous for new mutations in KCNJ13 which encodes the Kir 7.1 potassium channel, c.314G>T (p.Ser105Ile) in exon 2 and c.655C>T (p.Gln219*) in exon 3. Both mutations were absent from databases. CONCLUSION: KCNJ13 mutations are responsible for early-onset retinal dystrophy, featuring remarkable clumpy pigment deposits at the level of the retinal pigment epithelium, suggesting dysfunction and disorganization of this tissue. Parts of the retina remain relatively preserved anatomically but are increased in thickness. This distinct fundus appearance should help in identifying the "KCNJ13 retinal dystrophy" to orient the molecular diagnosis.

Uncommon Leber "plus" disease associated with mitochondrial mutation m.11778G>A in a premature child.

Leber hereditary optic neuropathy is a well-known mitochondrial disorder that leads to bilateral subacute visual failure. Although visual impairment is often the sole clinical feature, additional and severe neurologic abnormalities also have been documented for this disease. We report on a 13-year-old boy who has presented with severe visual failure since early childhood in a context of prematurity. In the first years of his life, clinical features included delayed psychomotor development and ataxia. The clinical presentation, which was initially attributed to prematurity, worsened thereafter, and the child developed acute neurologic degradation with the typical radiological findings of Leigh syndrome. The mitochondrial DNA point mutation 11778G>A was identified in the ND4 gene. The probable influence of environmental background on clinical expression of Leber optic neuropathy, particularly those of prematurity and oxygen therapy, is discussed in our manuscript.