Hereditary Cataract Research Articles

Clinical and genetic characterization of three families with Nance-Horan syndrome caused by NHS gene mutations

Objective: To explore the clinical phenotypes and pathogenic gene variation characteristics of three Chinese Han ethnic families affected by Nance-Horan syndrome, a rare X-linked genetic disorder. Methods: A pedigree investigation study was conducted at the First Affiliated Hospital of Zhengzhou University, collecting clinical data from three Chinese Han families with Nance-Horan syndrome between February 2009 and September 2018. Detailed family histories, comprehensive ophthalmological and systemic examinations were documented. Pedigree charts were created, and genetic inheritance patterns were analyzed to preliminarily diagnose the probands and other affected individuals. Genomic DNA was extracted from peripheral blood samples of family members, and next-generation sequencing was used to screen for target gene variations, which were confirmed by Sanger sequencing. Pathogenicity of the genetic variants and their impact on three-dimensional protein structure were analyzed using MutationTaster and computer-aided protein modeling. Results: In Family 1, there are 5 patients, including 4 females (aged 42, 37, 9 and 7) and 1 males (aged 12). In Family 2, there are 5 patients, including 3 females (aged 54, 32 and 16) and 2 males (aged 26 and 9). In Family 3, there are 8 patients, including 5 females (aged 69, 42, 37, 35 and 14) and 3 males (aged 10, 7 and 4). All probands in the three families exhibited nuclear cataracts with typical congenital hereditary cataract features, but no noticeable abnormalities in facial appearance or teeth. Next-generation sequencing identified new variation sites in the NHS gene, specifically c.2519_2520del, exon3del, and c.3847C>T. These variations included nonsense mutation p.(Ser840*), exon deletion p.(?), and nonsense mutation p.(Gln1283*). Combined clinical and genetic sequencing results confirmed X-linked Nance-Horan syndrome in all three families. Bioinformatics analysis indicated these variation sites were pathogenic and resulted in abnormal three-dimensional protein structures, likely being the main cause of Nance-Horan syndrome. Conclusion: The majority of patients from the three Nance-Horan syndrome families studied were affected by congenital hereditary cataracts characterized by nuclear opacities.The NHS gene variations c.2519_2520del, exon3del, and c.3847C>T are newly identified pathogenic sites in Nance-Horan syndrome, reported for the first time across three different families.

Participation of Lens Proteins and miRs in Traumatic and Inheritance Cataract: A Review on Diagnostic and Therapeutic Approaches for Cataract Management.

Traumatic and inherited cataract spiking blindness is caused by accumulated deposition of mutant eye lens protein or lens microarchitecture alteration. A traumatic cataract is a clouding of the eye's natural lens that occurs as a result of physical trauma to the eye. This trauma can be caused by various incidents such as blunt force injury, penetration by a foreign object, or a significant impact on the eye area. Inheritance cataracts or hereditary cataracts are cataracts that are genetically inherited from one or both parents. Complications following cataract surgery encompass various adverse outcomes such as inflammation, infection, bleeding, swelling, drooping eyelid, glaucoma, secondary cataracts, and complete loss of vision. The main purpose of the review is to highlight common pathophysiology associated with traumatic and inherited cataracts. Also, the review discusses diagnosis and treatment strategies for such cataract types by targeting their key pathological hallmarks. γD-crystallin plays a crucial role in maintaining the optical properties of the lens during the life span of an individual. Carbamazepine, Resveratrol, and Myricetin (CRM) are effectively bound at the γD-crystallin binding site and thereby could minimize misfolding and aggregation of γD-crystallin. miR-202, miR-193b, miR-135a, miR365, and miR-376a had the highest levels of abundance in the aqueous humor of individuals diagnosed with cataracts. The validation of these miRs will provide more insights into their functional roles and may be used for diagnostic purposes. The effective CRM combination as a multidrug formulation may postpone both traumatic and inherited cataracts and protect the eye from blindness.

Long-term visual outcomes and ocular complications in children with Marner's hereditary cataracts operated in the period 1940-2021.

To investigate visual development and long-term complications after cataract surgery in childhood. This cross-sectional study included patients from a family with Marner's hereditary cataracts who had cataract surgery before 18 years of age. The study was conducted from 1 January 2022 until 31 December 2022. The patients contributed to their medical files and participated in an updated ophthalmologic examination. We included 52 patients (101 eyes, 34 females). The median age at cataract surgery was 7 years (IQR: 5-10) and the age at examination was 40 years (IQR: 21-54). Primary and secondary intraocular lens implantation had been performed in 47.5% (25 patients, 48 eyes) and 16.8% (10 patients, 17 eyes). Visual acuity was ≤0.3 logMAR in 77% (78 eyes), and <0.5 logMAR in 8% (8 eyes). Glaucoma was present in 17% (9 patients, 12 eyes), ocular hypertension in 6% (3 patients, 4 eyes), and 10% (5 patients, 5 eyes) had prior retinal detachment. Mild visual field loss (2 < mean defect (MD) ≤ 6 dB) was found in 62% (63 eyes) and moderate to advanced visual field loss (MD > 6 dB) in 24% (24 eyes). Thirty-five patients (67%) held a driver's licence, and three were not allowed to drive due to low visual function. All patients were employed. After cataract surgery in childhood, many patients achieve normal visual acuity, but mild visual field loss is common. Long-term follow-up is important due to the high risk of glaucoma.

The cost of genetic diagnosis of suspected hereditary pediatric cataracts with whole-exome sequencing from a middle-income country perspective: a mixed costing analysis

Up to 25% of pediatric cataract cases are inherited. There is sparse information in the literature regarding the cost of whole-exome sequencing (WES) for suspected hereditary pediatric cataracts. Molecular diagnosis of suspected hereditary pediatric cataracts is important for comprehensive genetic counseling. We performed a partial economic evaluation with a mixed costing analysis, using reimbursement data and microcosting approach with a bottom-up technique to estimate the cost of using WES for genetic diagnosis of suspected hereditary pediatric cataracts from the perspective of the Brazilian governmental health care system. One hundred and ten participants from twenty-nine families in Rio de Janeiro (RJ) were included. Costs of consumables, staff and equipment were calculated. Two scenarios were created: (1) The reference scenario included patients from RJ with suspected hereditary pediatric cataracts plus two family members. (2) The alternative scenario considered other genetic diseases, resulting in 5,280 exams per month. Sensitivity analysis was also performed. In the reference scenario, the total cost per exam was 700.09 United States dollars (USD), and in the alternative scenario, the total cost was 559.23 USD. The cost of WES alone was 527.85 USD in the reference scenario and 386.98 USD in the alternative scenario. Sensitivity analysis revealed that the largest costs were associated with consumables in both scenarios. Economic evaluations can help inform policy decisions, especially in middle-income countries such as Brazil.

Long-term risk of glaucoma after cataract surgery in childhood.

To examine the long-term risk of glaucoma after cataract surgery in childhood. This study took place from January 2022 until December 2022 and included patients from a large family with hereditary childhood cataract who had cataract surgery before 18 years of age. Patients underwent an ophthalmologic examination to determine the presence of glaucoma or ocular hypertension (OHT). Patients who did not want to participate in the examination could contribute with a medical journal from their treating ophthalmologist. The risk of long-term glaucoma was determined using survival analysis, and risk factors were assessed using a Cox proportional hazards regression model. We included 68 patients (133 eyes) with a median age at cataract surgery of 7 years (IQR: 5-10). The median follow-up time after cataract surgery to glaucoma/OHT or the latest ophthalmologic examination was 35 years (IQR: 15-48). Twelve patients (18 eyes) had glaucoma, and five patients (eight eyes) had OHT, resulting in 15 patients with glaucoma/OHT. The long-term risk of glaucoma/OHT diagnosed in adulthood was 47.7% (CI: 21.8-70.9) at the age of 70 years of patients who were free of glaucoma before their 18th year. We could not confirm or dismiss an association between glaucoma/OHT and sex, age at surgery, number of ocular interventions before 18 years of age or glaucoma after cataract surgery in a first-degree relative. Cataract surgery in childhood is associated with a high risk of late-onset glaucoma. Regular lifelong follow-up is important to ensure early diagnosis and prevent extensive vision loss.

Canine cataracts

The intraocular lens is uniquely designed to aid focused vision, and diseases of the lens such as cataracts are a common cause of blindness in dogs. The causes of cataracts are discussed including the main aetiologies such as hereditary cataract, senile and diabetic cataracts. The article focuses on dogs, as cataracts are less common in cats, although traumatic cataracts and rarely, inherited, congenital and developmental cataracts do occur in felines. The article discusses ways to examine and classify a cataract; the best way to diagnose an early cataract is examination with a veterinary ophthalmologist. Early detection is important, as it is not advised to breed from dogs affected with hereditary cataracts. Surgical extraction is currently the only method to remove a cataract and restore vision, and the common complications of cataract surgery are also explored.

Multiocular defect in the Old English Sheepdog: A canine form of Stickler syndrome type II associated with a missense variant in the collagen-type gene COL11A1.

Multiocular defect has been described in different canine breeds, including the Old English Sheepdog. Affected dogs typically present with multiple and various ocular abnormalities. We carried out whole genome sequencing on an Old English Sheepdog that had been diagnosed with hereditary cataracts at the age of five and then referred to a board-certified veterinary ophthalmologist due to owner-reported visual deterioration. An ophthalmic assessment revealed that there was bilateral vitreal degeneration, macrophthalmos, and spherophakia in addition to cataracts. Follow-up consultations revealed cataract progression, retinal detachment, uveitis and secondary glaucoma. Whole genome sequence filtered variants private to the case, shared with another Old English Sheepdog genome and predicted to be deleterious were genotyped in an initial cohort of six Old English Sheepdogs (three affected by multiocular defect and three control dogs without evidence of inherited eye disease). Only one of the twenty-two variants segregated correctly with multiocular defect. The variant is a single nucleotide substitution, located in the collagen-type gene COL11A1, c.1775T>C, that causes an amino acid change, p.Phe1592Ser. Genotyping of an additional 14 Old English Sheepdogs affected by multiocular defect revealed a dominant mode of inheritance with four cases heterozygous for the variant. Further genotyping of hereditary cataract-affected Old English Sheepdogs revealed segregation of the variant in eight out of nine dogs. In humans, variants in the COL11A1 gene are associated with Stickler syndrome type II, also dominantly inherited.

Allele and genotype frequencies for primary hereditary cataract, multifocal retinopathy 1, and degenerative myelopathy in Pyrenean Mountain dog from Italy

Pyrenean Mountain Dog (PMD) is an ancient dog breed firstly described in XIV century in the Pyrenees Region and nowadays diffused both in Europe and in the US. Hereditary Cataract (HC), defined as the inherited opacity of the lens, involves clinical signs ranging from reduced vision to glaucoma. A molecular basis of HC was firstly described in Staffordshire Bull Terriers and then reported in multiple canine breeds. The HC-associated variation is a single nucleotide deletion in HSF4 gene that introduces a premature stop codon (c.962del, p.Ala321*). Multifocal Retinopathy 1 (MR) is an ocular disorder characterized by multiple areas of retinal degeneration, caused in various dog breeds (including PMD) by a single nucleotide variant (SNV) in BEST1 gene that generates a premature stop codon (c.73G>A, p.Arg25*). Degenerative Myelopathy (DM) is an adult-onset, progressive neurodegenerative disease and it is associated to a SNV in SOD1 gene causing a change in aminoacidic sequence of the protein (c.118G>A, p.Glu40Lys). This causative variant has been described in various dog breeds, including PMD. Aim of this study was to determine the allele frequencies for the abovementioned three genetic diseases in the Italian breeding PMD population. The survey found no dogs carrying the allele (deletion) associated with HC, while three dogs (6 %) were heterozygous (G/A) for the MR-associated variant, and seven dogs (13 %) were heterozygous (G/A) for the DM-associated alteration, indicating that the variant alleles frequency were 0 %, 3 %, and 7 %, respectively. Appropriate mating management is suggested for the prevention of genetic diseases spreading in the PMD population.

Gene profiles and mutations in the development of cataracts in the ICR rat model of hereditary cataracts

Cataracts are opacifications of the lens that cause loss of visual acuity and ultimately of eyesight. Age-related cataract develops in most elderly people, but the mechanisms of cataract onset are incompletely understood. The Ihara Cataract Rat (ICR) is an animal model of hereditary cataracts showing cortical opacity that commonly develops prematurely. We identified putative mechanisms of cataract onset in the ICR rat model by measuring gene expression changes before and after cortical cataract development and conducting point mutation analysis. Genes differentially expressed between 4-week-old animals without cortical cataracts and 8–10-week-old animals with cortical cataracts were selected from microarray analysis. Three connections were identified by STRING analysis: (i) Epithelial-Mesenchymal Transition (EMT), including Col1a2, and Pik3r1. (ii) Lens homeostasis, including Aqp5, and Cpm. (iii) Lipid metabolism, including Scd1, Srebf1, and Pnpla3. Subsequently, mutation points were selected by comparing ICR rats with 12 different rats that do not develop cataracts. The apolipoprotein Apoc3 was mutated in ICR rats. Analyses of gene expression changes and point and mutations suggested that abnormalities in EMT or lipid metabolism could contribute to cataract development in ICR rats.

The 18th amino acid glycine plays an essential role in maintaining the structural stabilities of γS-crystallin linking with congenital cataract

γS-crystallin is particularly rich in the embryonic nuclear region and is crucial to the maintenance of lens transparency and optical properties. Gene mutations in crystallin are the main factors leading to congenital hereditary cataracts, which are a major cause of visual impairment in children. Some mutations located in the 18th amino acid glycine of γS-crystallin were reported to be linking with congenital cataracts. However, the pathogenic mechanism has not been elucidated. Interestingly, we previously identified a novel variant of γS-crystallin (c.53G > A; p. G18D) with progressive cortical and sutural congenital cataracts in one Chinese family. In this study, we purified the γS-crystallin wildtype and mutant proteins to investigate the effects of the G18D mutation on the structural stability of γS-crystallin. The results showed that there were tertiary structural differences between the wild-type γS-crystallin and the G18D variant. The mutation significantly impaired the stability of γS-crystallin under environmental stress and promoted aggregation. Furthermore, molecular dynamics (MD) simulations showed that the mutation altered H-bonding and surface electrostatic potential. Significantly decreased stability along with an increased tendency to aggregate under environmental stress may be the major pathogenic factors for cataracts induced by the G18D mutation.

Study of The Molecular Nature of Congenital Cataracts in Patients from The Volga–Ural Region

Hereditary cataracts are characterized by significant clinical and genetic heterogeneity, which can pose challenges for early DNA diagnosis. To comprehensively address this problem, it is essential to investigate the epidemiology of the disease, perform population studies to determine the spectrum and frequencies of mutations in the responsible genes, and examine clinical and genetic correlations. Based on modern concepts, non-syndromic hereditary cataracts are predominantly caused by genetic disease forms associated with mutations in crystallin and connexin genes. Therefore, a comprehensive approach to studying hereditary cataracts is necessary for early diagnosis and improved treatment outcomes. The crystallin (CRYAA, CRYAB, CRYGC, CRYGD, and CRYBA1) and connexin (GJA8, GJA3) genes were analyzed in 45 unrelated families from the Volga–Ural Region (VUR) with hereditary congenital cataracts. Pathogenic and probably pathogenic nucleotide variants were identified in ten unrelated families, nine of which had cataracts in an autosomal dominant pattern of inheritance. Two previously undescribed likely pathogenic missense variants were identified in the CRYAA gene: c.253C &gt; T (p.L85F) in one family and c.291C &gt; G (p.H97Q) in two families. The known mutation c.272_274delGAG (p.G91del) was found in the CRYBA1 gene in one family, while no pathogenic variants were found in the CRYAB, CRYGC, or CRYGD genes in the examined patients. In the GJA8 gene, the known mutation c.68G &gt; C (p.R23T) was found in two families, and previously undescribed variants were identified in two other families: a c.133_142del deletion (p.W45Sfs*72) and a missense variant, c.179G &gt; A (p.G60D). In one patient with a recessive form of cataract, two compound-heterozygous variants were identified—a previously undescribed likely pathogenic missense variant, c.143A &gt; G (p.E48G), and a known variant with uncertain pathogenetic significance, c.741T &gt; G (p.I24M). Additionally, a previously undescribed deletion, c.del1126_1139 (p.D376Qfs*69), was identified in the GJA3 gene in one family. In all families where mutations were identified, cataracts were diagnosed either immediately after birth or during the first year of life. The clinical presentation of the cataracts varied depending on the type of lens opacity, resulting in various clinical forms. This information emphasizes the importance of early diagnosis and genetic testing for hereditary congenital cataracts to guide appropriate management and improve outcomes.

Screening the pathogenic causes of congenital cataract via whole exome sequencing technology in three families: Molecular genetics of congenital cataract.

Congenital cataract is the commonest cause of visual impairment and blindness in children worldwide. Among congenital cataract cases, ~25% are caused by genetic defects, while several genetic mutations have been identified in hereditary cataract. In the present study, a patient with cataract underwent clinical ophthalmic examination and pedigree analysis. Whole exome sequencing and Sanger sequencing were performed to identify and verify gene mutations. The frequency, conservation, pathogenicity and hydrophobicity of the mutated amino acids were analyzed by bioinformatics analysis. The clinical examination and investigation verified that the probands of familyA and C suffered from nuclear cataracts. In addition, the proband of familyB was diagnosed with white punctate opacity. The pattern of inheritance was autosomal dominant. The sequencing analysis results revealed a mutation c.592-c593insG (p.W198Wfs*22) in exon6 of CRYBA1/A3, a known mutation c.463C >T (p.Q155X) in exon6 of CRYBB2 and a third mutation c.865‑c.866insC (p.T289Tfs*91) in exon2 of GJA8. Each variant was co‑segregated with disease in familyAnd the mutation frequency in the database was <0.01. It has been reported that the mutation sites are highly conserved among different species, thus greatly affecting the sequence and structure of a protein, while exhibiting high pathogenicity in theory. The two crystallin gene mutations could notably enhance the local hydrophobicity of the protein, eventually resulting in its reduced solubility and destruction of lens transparency. The current study identified pathogenic genes in three families with congenital cataract and analyzed the association between mutation sites and different cataract phenotypes. Overall, the results could expand the genotype spectrum of congenital cataract and provide evidence for its clinical diagnosis.

Insight into Pathogenic Mechanism Underlying the Hereditary Cataract Caused by βB2-G149V Mutation

Congenital cataracts account for approximately 5-20% of childhood blindness worldwide and 22-30% of childhood blindness in developing countries. Genetic disorders are the primary cause of congenital cataracts. In this work, we investigated the underlying molecular mechanism of G149V point missense mutation in βB2-crystallin, which was first identified in a three-generation Chinese family with two affected members diagnosed with congenital cataracts. Spectroscopic experiments were performed to determine the structural differences between the wild type (WT) and the G149V mutant of βB2-crystallin. The results showed that the G149V mutation significantly changed the secondary and tertiary structure of βB2-crystallin. The polarity of the tryptophan microenvironment and the hydrophobicity of the mutant protein increased. The G149V mutation made the protein structure loose and the interaction between oligomers was reduced, which decreased the stability of the protein. Furthermore, we compared βB2-crystallin WT and the G149V mutant with their biophysical properties under environmental stress. We found that the G149V mutation makes βB2-crystallin more sensitive to environmental stresses (oxidative stress, UV irradiation, and heat shock) and more likely to aggregate and form precipitation. These features might be important to the pathogenesis of βB2-crystallin G149V mutant related to congenital cataracts.

Whole-exome sequencing prioritizes candidate genes for hereditary cataract in the Emory mouse mutant.

The Emory cataract (Em) mouse mutant has long been proposed as an animal model for age-related or senile cataract in humans-a leading cause of visual impairment. However, the genetic defect(s) underlying the autosomal dominant Em phenotype remains elusive. Here, we confirmed development of the cataract phenotype in commercially available Em/J mice [but not ancestral Carworth Farms White (CFW) mice] at 6-8 months of age and undertook whole-exome sequencing of candidate genes for Em. Analysis of coding and splice-site variants did not identify any disease-causing/associated mutations in over 450 genes known to underlie inherited and age-related forms of cataract and other lens disorders in humans and mice, including genes for lens crystallins, membrane/cytoskeleton proteins, DNA/RNA-binding proteins, and those associated with syndromic/systemic forms of cataract. However, we identified three cataract/lens-associated genes each with one novel homozygous variant including predicted missense substitutions in Prx (p.R167C) and Adamts10 (p.P761L) and a disruptive in-frame deletion variant (predicted missense) in Abhd12 (p.L30_A32delinsS) that were absent in CFW and over 35 other mouse strains. In silico analysis predicted that the missense substitutions in Prx and Adamts10 were borderline neutral/damaging and neutral, respectively, at the protein function level, whereas, that in Abhd12 was functionally damaging. Both the human counterparts of Adamts10 and Abhd12 are clinically associated with syndromic forms of cataract known as Weil-Marchesani syndrome 1 and polyneuropathy, hearing loss, ataxia, retinitis pigmentosa, and cataract syndrome, respectively. Overall, while we cannot exclude Prx and Adamts10, our data suggest that Abhd12 is a promising candidate gene for cataract in the Em/J mouse.

Synthesizing mRNA To Treat Hereditary Cataracts

Synthesizing mRNA To Treat Hereditary Cataracts

The incidence of genetic disease alleles in Australian Shepherd dog breed in European countries.

Genetic disease control is generally not given the importance it deserves. Information about what percentage of individuals carry a disorder-causing mutation is crucial for breeders to produce healthy offspring and maintain a healthy dog population of a particular breed. This study aims to provide information about the incidence of mutant alleles for the most frequently occurring hereditary diseases in the Australian Shepherd dog breed (AS). The samples were collected during a 10-years period (2012-2022) in the European population of the AS. Mutant alleles and incidence were calculated from all the obtained data for all the diseases, specifically: collie eye anomaly (9.71%), canine multifocal retinopathy type 1 (0.53%), hereditary cataract (11.64%), progressive rod-cone degeneration (1.58%), degenerative myelopathy (11.77%) and bob-tail/short-tail (31.74%). Our data provide more information to dog breeders to support their effort to limit the spread of hereditary diseases.

Síndrome de hiperferritinemia e catarata hereditária: relato de caso

INTRODUCTION: The increase in ferritin is a common finding in clinical practice, and may have several causes, such as inflammatory, neoplastic and liver diseases. In addition, ferritin represents the bodys iron stores. The syndrome of hereditary hyperferritinemia and cataract (SHHC) is a rare pathology, which is part of the differential diagnosis of the causes of increased ferritin. The diagnosis of SHHC has a great impact for the patient, as it avoids unnecessary therapeutic interventions, such as bleeding. DESCRIPTION: In the present study, a case of SHHC in a healthy preschooler is reported, in which the finding of elevated ferritin was obtained in an occasional test. The child was submitted to an extensive diagnostic procedure, performed to rule out other causes. DISCUSSION: The prevalence of SHHC is unknown in Brazil, and its variable penetrance can make it difficult to perceive the hereditary character. Thus, this case report and literature review has the importance of alerting about the existence of the pathology, so that pediatricians and other health professionals can make this diagnosis.

A Novel Mutation in the FYCO1 Gene Causing Congenital Cataract: Case Study of a Chinese Family.

Congenital cataract is the most important global cause of visual impairment in children. Autosomal dominant and autosomal recessive inheritance account for the majority of the hereditary nonsyndromic congenital cataract. The function of FYCO1 gene is to guide the transport of the microtubule-directed vesicles. Mutations in the FYCO1 gene may cause cataracts. We reported a novel nonsense mutation in FYCO1 (c.1411C > T, P. R471 ∗), which could cause nonsyndrome autosomal recessive congenital cataract. We underwent an ophthalmology examination of all participants and collected blood samples from all participants and extracted genomic DNAs. By whole exome sequencing, we found that this family carried an unreported mutation in the FYCO1 gene: c.1411C > T, P. R471 ∗. Sanger sequencing was performed to verify the mutation. We used ITASSER and PYMOL to predict and compare the structure and function of the mutated proteins. Using SIFT software and referring to the relevant guidelines of ACMG, the mutation was determined to be pathogenic. The models suggested that the nonsense mutation p.R471∗ resulted in a profound disruption of the FYCO1 protein structure. This report expands the locus information of the FYCO1 mutations.

Systemic and ocular associations in pediatric patients undergoing cataract surgery.

Evaluation for systemic diagnosis is an important part of pediatric cataract management. While there are reports on associated systemic and ocular associations in children with infantile cataracts, reports specifying associations in large cohorts of children undergoing cataract surgery are lacking. Retrospective chart review of consecutive patients undergoing cataract surgery at a pediatric tertiary referral center during 30-year period was performed. Associated systemic and ocular associations were recorded. The etiologies were analyzed depending on laterality, age, and gender. Seven-hundred twenty-seven patients (1135 eyes) were included for analysis: 408 (56%) with bilateral and 319 (44%) with unilateral cataract. An identifiable cause for cataract was identified in 66% (270/408) bilateral and 55% (176/319) unilateral cataract patients. Hereditary cataract accounted for 22% of bilateral cataracts. An underlying syndrome or genetic diagnosis was found in 24% bilateral (97/408, 86 genetic/syndromic, 11 metabolic) but only in 2% of unilateral cases (5/319). Cataracts were the result of treatment for cancer, or other systemic conditions requiring steroids, in 60/408 bilateral (15%) and 15/319 (5%) unilateral cataract patients. In contrast, unilateral cataracts had higher ocular associations (49%, 156/319) than bilateral cataracts (6%, 23/408) primarily ocular trauma (20%, 64/319) and persistent fetal vasculature (20%, 62/319). Clinicians should be aware of potential systemic and ocular associations among children with visually significant cataracts. Those with no family history of juvenile cataract should be evaluated for systemic associations, and referral to genetics may be warranted in select cases.

Identification of a New Mutation p.P88L in Connexin 50 Associated with Dominant Congenital Cataract.

Congenital hereditary cataract is genetically heterogeneous and the leading cause of visual impairment in children. Identification of hereditary causes is critical to genetic counselling and family planning. Here, we examined a four-generation Chinese pedigree with congenital dominant cataract and identified a new mutation in GJA8 via targeted exome sequencing. A heterozygous missense mutation c.263C > T, leading to a proline-to-Leucine conversion at the conserved residue 88 in the second transmembrane domain of human connexin 50 (Cx50), was identified in all patients but not in unaffected family members. Functional analyses of the mutation revealed that it disrupted the stability of Cx50 and had a deleterious effect on protein function. Indeed, the mutation compromised normal membrane permeability and gating of ions, and impeded cell migration when overexpressed. Together, our results expand the pathogenic mutation spectrum of Cx50 underlying congenital cataract and lend more support to clinical diagnosis and genetic counseling.