TEK gene-related primary congenital glaucoma: Phenotypic features and mutational spectrum in a Mexican cohort of 10 unrelated families.

Primary congenital glaucoma (PCG) is one of the leading causes of visual damage and blindness, severely affecting the quality of life of affected children. It is characterized by cupping of the optic disc and loss of ganglion cells due to elevated intraocular pressure. While most PCG patients exhibit epiphora, photophobia, and buphthalmos with corneal opacity, variability in phenotypic manifestations is not uncommon. Prompt diagnosis and treatment of PCG affected individuals becomes relevant to preserve visual function throughout their lives. Most PCG cases are sporadic or autosomal recessive; however, an incompletely dominant autosomal dominant form arising from mutations in the TEK gene has recently been demonstrated. Here, we describe the clinical and mutational features of a cohort of Mexican patients with TEK-related PCG. Our results support the involvement of the TEK gene as an important cause of the disease in our ethnic group and expand the mutational spectrum causing PCG by reporting 10 novel disease-causing variants.

USH2A mutational spectrum causing syndromic and non-syndromic retinal dystrophies in a large cohort of Mexican patients.

Background: Mutations in the USH2A gene are the leading cause of both non-syndromic autosomal recessive retinitis pigmentosa (RP) and Usher syndrome, a syndromic form of RP characterized by retinal dystrophy and sensorineural hearing loss. To contribute to the expansion of the USH2A-related molecular spectrum, the results of genetic screening in a large cohort of Mexican patients are presented. Methods: The study population comprised 61 patients with a clinical diagnosis of either non-syndromic RP (n = 30) or Usher syndrome type 2 (USH2; n = 31) who were demonstrated to carry biallelic pathogenic variants in USH2A in a three-year period. Genetic screening was performed either by gene panel sequencing or by exome sequencing. A total of 72 available first- or second-degree relatives were also genotyped for familial segregation of the identified variants. Results: The USH2A mutational spectrum in RP patients included 39 distinct pathogenic variants, most of them of the missense type. The most common RP-causing variants were p.Cys759Phe (c.2276G>T), p.Glu767Serfs*21 (c.2299delG), and p.Cys319Tyr (c.956G>A), which together accounted for 25% of all RP variants. Novel USH2A mutations included three nonsense, two missense, two frameshift, and one intragenic deletion. The USH2A mutational spectrum in USH2 patients included 26 distinct pathogenic variants, most of them of the nonsense and frameshift types. The most common Usher syndrome-causing variants were p.Glu767Serfs*21 (c.2299delG), p.Arg334Trp (c.1000C>T), and c.12067-2A>G), which together accounted for 42% of all USH2-related variants. Novel Usher syndrome USH2A mutations included six nonsense, four frameshift, and two missense mutations. The c.2299delG mutation was associated with a common haplotype for SNPs located in exons 2-21 of USH2A, indicating a founder mutation effect. Conclusions: Our work expands the USH2A mutational profile by identifying 20 novel pathogenic variants causing syndromic and non-syndromic retinal dystrophy. The prevalent c.2299delG allele is shown to arise from a founder effect. Our results emphasize the usefulness of molecular screening in underrepresented populations for a better characterization of the molecular spectrum of common monogenic diseases.

Clinical-genetic findings in a group of subjects with macular dystrophies due to mutations in rare inherited retinopathy genes.

PURPOSE: To describe the results of clinical and molecular analyses in a group of patients suffering from inherited macular dystrophies, in which next-generation sequencing (NGS) efficiently detected rare causative mutations. METHODS: A total of eight unrelated Mexican subjects with a clinical and multimodal imaging diagnosis of macular dystrophy were included. Visual assessment methods included best corrected visual acuity, color fundus photography, Goldmann visual field tests, kinetic perimetry, dark/light adapted chromatic perimetry, full-field electroretinography, autofluorescence imaging, and spectral domain-optical coherence tomography imaging. Genetic screening was performed by means of whole exome sequencing with subsequent Sanger sequencing validation of causal variants. RESULTS: All patients exhibited a predominantly macular or cone-dominant disease. Patients' ages ranged from 12 to 60 years. Three cases had mutations in genes associated with autosomal dominant inheritance (UNC119 and PRPH2) while the remaining five cases had mutations in genes associated with autosomal recessive inheritance (CNGA3, POC1B, BEST1, CYP2U1, and PROM1). Of the total of 11 different pathogenic alleles identified, three were previously unreported disease-causing variants. CONCLUSIONS: Macular dystrophies can be caused by defects in genes that are not routinely analyzed or not included in NGS gene panels. In this group of patients, whole exome sequencing efficiently detected rare genetic causes of hereditary maculopathies, and our findings contribute to expanding the current knowledge of the clinical and mutational spectrum associated with these disorders.

Ophthalmic findings in patients with autosomal recessive lamellar ichthyosis due to TGM1 mutations in an isolated population.

PURPOSE: To describe the ocular clinical characteristics of a group of Mexican patients with lamellar ichthyosis (LI) arising from TGM1 pathogenic variants. METHODS: Ophthalmological exploration, pedigree analysis and genetic screening were performed in patients with an established clinical diagnosis of lamellar ichthyosis from families located in a small community in the Southeast of Mexico. RESULTS: Nine patients with LI in five families were identified. There were six affected females. All patients (9/9) demonstrated eye lid abnormalities with eight patients showing lid margin abnormalities. Madarosis was present in only three individuals and corneal scarring was documented in two. All nine individuals carried biallelic TGM1 variants, either homozygously or as compound heterozygous. CONCLUSION: Ocular anomalies are common in individuals with TGM1-related LI. The occurrence of a variety of private or rare mutations hampers the identification of a genotype-phenotype correlation for ocular anomalies in this disorder.

A novel homozygous ZNF469 variant causing brittle cornea syndrome is associated with corneal ectasias in heterozygous carriers.

AIM: To describe a family segregating a novel truncating ZNF469 homozygous mutation causing brittle cornea syndrome type 1 in a male patient and associated with corneal ectasia in his two heterozygous young children. METHODS: A 49-year-old affected male and his 12- and 8-year-old, apparently healthy, siblings underwent phenotypic and genetic assessment. An Oculus Pentacam Scheimpflug topographer system was employed for keratometries and central corneal thickness measurements. Exome sequencing was performed in DNA from the index case with subsequent Sanger sequencing confirmation of the ZNF469 gene causal variant in his relatives. RESULTS: The index case had a history of bilateral keratoglobus, corneal perforations, bilateral hypoacusia, and skeletal anomalies. His two children exhibited topographic anomalies compatible with keratoconus suspects as well as mild skeletal anomalies. Genetic analysis identified a novel homozygous c.2340delC variant in the ZNF469 gene, which predicts a p.(Arg781Glufs*19) truncated protein. Sanger sequencing identified heterozygosity for the c.2340delC variant in DNA from both siblings. CONCLUSION: Our results expand the mutational spectrum associated with brittle cornea syndrome and provide the first demonstration of early corneal anomalies in subjects carrying monoallelic ZNF469 variants.

AUTOSOMAL DOMINANT MÜLLER CELL SHEEN DYSTROPHY: Clinical, Histopathologic, and Genetic Assessment in an Extended Family With Long Follow-Up.

BACKGROUND: Autosomal dominant Müller cell dystrophy is a rare condition we described in 1991. It is characterized by a striking sheen appearance on the retinal surface with progressive retinal changes leading to disorganization and atrophy with a decreased b-wave electroretinograms. MATERIALS AND METHODS: We examined 45 members of a 4-generation family. Fifteen subjects from three generations were found with the disease, without gender predilection. Seven patients underwent ophthalmic examination including fundus examination, intravenous fluorescein angiogram, spectral-domain optical coherence tomography, and electroretinogram. Six patients have a 30-year follow-up. Histopathology examination was performed on eyes of the eldest patient. Whole exome sequencing was done in four affected subjects. RESULTS: Findings include a decreased visual acuity, abnormal cellophane-like sheen of the vitreoretinal interface, a "plush" nerve fiber layer, and characteristic macular changes. Electroretinogram showed a selective b-wave diminution. Intravenous fluorescein angiogram presented perifoveal hyperfluorescence and capillary leakage. Spectral-domain optical coherence tomography revealed cavitations involving inner and later outer retinal layers with later disorganization. Histopathologic findings included Müller cell abnormalities with cystic disruption of inner retinal layers, pseudoexfoliation in anterior segment, and amyloidosis of extraocular vessels. Pedigree analysis suggests an autosomal dominant inheritance with late onset. DNA analysis demonstrated a previously undescribed heterozygous missense p.Glu109Val mutation in transthyretin. CONCLUSION: To the best of our knowledge, this is the first family reported with this disorder. Our data support the hypothesis that autosomal dominant Müller cell dystrophy is a distinct retinal dystrophy affecting Müller cells. Mutations in transthyretin gene may manifest as a predominantly retinal disorder.

Clinical, histopathological, and in silico pathogenicity analyses in a pedigree with familial amyloidosis of the Finnish type (Meretoja syndrome) caused by a novel gelsolin mutation.

Purpose: Familial amyloidosis of the Finnish type (FAF) is an inherited amyloidosis arising from mutations in the gelsolin protein (GSN). The disease includes facial paralysis, loose skin, and lattice corneal dystrophy. To date, FAF has been invariably associated with substitution of Asp214 in GSN. We describe the clinical, histopathological, and genetic features of a family with FAF due to a novel GSN mutation. Methods: Five affected adult individuals in a three-generation FAF pedigree were included in the study. Histopathological analysis was performed on an eyelid skin biopsy from one patient. Genetic analysis included next-generation sequencing (NGS) and Sanger sequencing for confirmation of the GSN variant. Several tools for in silico analysis of pathogenicity for the novel variant and to predict the effect of the amino acid replacement on protein stability were used. Results: Three older adult affected patients exhibited corneal lattice dystrophy, cutis laxa, and facultative peripheral neuropathy. Two younger adult individuals presented only with corneal amyloid deposits. NGS identified a heterozygous GSN c.1631T>G transversion, predicting a novel p.Met544Arg mutation. All in silico tools indicated that p.Met544Arg is deleterious for GSN functionality or stability. Conclusions: The results expand the molecular spectrum of GSN-linked systemic amyloidosis. The novel p.Met544Arg pathogenic variant is predicted to affect gelsolin function, presumably by impairing a potential calcium-sensitive, actin-binding region.

Exome sequencing identifies a SREBF1 recurrent ARG557CYS mutation as the cause of hereditary mucoepithelial dysplasia in a family with high clinical variability.

Hereditary mucoepithelial dysplasia (HMD) is an uncommon autosomal dominant disease affecting skin, mucosae, hair, eyes, and lungs. Prominent clinical features include non-scarring alopecia, mucosal erythema, perineal erythematous intertrigo, and involvement of the conjunctival mucosa. To date, 20 familial or sporadic HMD cases have been described, most of them originating from Caucasian ethnic groups. In this study, a novel HMD pedigree, including an affected father and his daughter, is reported. Clinical expression showed significant differences in affected subjects, especially in the distribution and severity of skin lesions. Exome sequencing demonstrated that both affected subjects carried a heterozygous c.1669C>T (p.Arg557Cys) pathogenic variant in the SREBF1 gene. Our results improve the knowledge of the clinical and genetic features of HMD. In addition, a comparative review of the clinical features of all published HMD cases is presented.

Extracranial midline defects in a patient with craniofrontonasal syndrome with a novel EFNB1 mutation.

We report a female patient with craniofrontonasal syndrome (CFNS) who in addition showed other cranial and extracranial midline defects including partial corpus callosum agenesis, ocular melanocytosis, pigmentary glaucoma, duplex collecting system, uterus didelphys, and septate vagina. She was found to have a novel pathogenic variant in exon 5 of EFNB1, c.646G>T (p.Glu216*) predicted to cause premature protein truncation. From our review, we found at least 39 published CFNS patients with extracranial midline defects, comprising congenital diaphragmatic hernia, congenital heart defects, umbilical hernia, hypospadias, and less frequently, sacrococcygeal teratomas, and internal genital anomalies in females. These findings support that the EFNB1 mutations have systemic consequences disrupting morphogenetic events at the extracranial midline. Though these are not rigorously included as midline defects, we found at least 10 CFNS patients with congenital anomalies of the kidney and urinary tract, all females. Additionally, uterus didelphys and ocular melanocytosis observed in our patient are proposed also as a previously unreported EFNB1-related midline defects. In addition, this case may be useful for considering the intentional search for genitourinary anomalies in future patients with CFNS, which will be helpful to define their frequency in this entity.

Identification of novel pathogenic variants and novel gene-phenotype correlations in Mexican subjects with microphthalmia and/or anophthalmia by next-generation sequencing.

Severe congenital eye malformations, particularly microphthalmia and anophthalmia, are one of the main causes of visual handicap worldwide. They can arise from multifactorial, chromosomal, or monogenic factors and can be associated with extensive clinical variability. Genetic analysis of individuals with these defects has allowed the recognition of dozens of genes whose mutations lead to disruption of normal ocular embryonic development. Recent application of next generation sequencing (NGS) techniques for genetic screening of patients with congenital eye defects has greatly improved the recognition of monogenic cases. In this study, we applied clinical exome NGS to a group of 14 Mexican patients (including 7 familial and 7 sporadic cases) with microphthalmia and/or anophthalmia. Causal or likely causal pathogenic variants were demonstrated in ~60% (8 out of 14 patients) individuals. Seven out of 8 different identified mutations occurred in well-known microphthalmia/anophthalmia genes (OTX2, VSX2, MFRP, VSX1) or in genes associated with syndromes that include ocular defects (CHD7, COL4A1) (including two instances of CHD7 pathogenic variants). A single pathogenic variant was identified in PIEZO2, a gene that was not previously associated with isolated ocular defects. NGS efficiently identified the genetic etiology of microphthalmia/anophthalmia in ~60% of cases included in this cohort, the first from Mexican origin analyzed to date. The molecular defects identified through clinical exome sequencing in this study expands the phenotypic spectra of CHD7-associated disorders and implicate PIEZO2 as a candidate gene for major eye developmental defects.

Retinal phenotypic characterization of patients with ABCA4 retinopathydue to the homozygous p.Ala1773Val mutation.

Purpose: To describe the retinal clinical features of a group of Mexican patients with Stargardt disease carrying the uncommon p.Ala1773Val founder mutation in ABCA4. Methods: Ten patients carrying the p.Ala1773Val mutation, nine of them homozygously, were included. Visual function studies included best-corrected visual acuity, electroretinography, Goldmann kinetic visual fields, and full-field electroretinography (ERG). In addition, imaging studies, such as optical coherence tomography (OCT), short-wave autofluorescence imaging, and quantitative analyses of hypofluorescence, were performed in each patient. Results: Best-corrected visual acuities ranged from 20/200 to 4/200. The median age of the patients at diagnosis was 23.3 years. The majority of the patients had photophobia and nyctalopia, and were classified as Fishman stage 4 (widespread choriocapillaris atrophy, resorption of flecks, and greatly reduced ERG amplitudes). An atypical retinal pigmentation pattern was observed in the patients, and the majority showed cone-rod dystrophy on full-field ERG. In vivo retinal microstructure assessment with OCT demonstrated central retinal thinning, variable loss of photoreceptors, and three different patterns of structural retinal degeneration. Two dissimilar patterns of abnormal autofluorescence were observed. No apparent age-related differences in the pattern of retinal degeneration were observed. Conclusions: The results indicate that this particular mutation in ABCA4 is associated with a severe retinal phenotype and thus, could be classified as null. Careful phenotyping of patients carrying specific mutations in ABCA4 is essential to enhance our understanding of disease expression linked to particular mutations and the resulting genotype-phenotype correlations.

Extension of the mutational and clinical spectrum of SOX2 related disorders: Description of six new cases and a novel association with suprasellar teratoma.

SOX2 is a transcription factor that is essential for maintenance of pluripotency and has several conserved roles in early embryonic development. Heterozygous loss-of-function variants in SOX2 are identified in approximately 40% of all cases of bilateral anophthalmia/micropthalmia (A/M). Increasingly SOX2 mutation-positive patients without major eye findings, but with a range of other developmental disorders including autism, mild to moderate intellectual disability with or without structural brain changes, esophageal atresia, urogenital anomalies, and endocrinopathy are being reported, suggesting that the clinical phenotype associated with SOX2 loss is much broader than previously appreciated. In this report we describe six new cases, four of which carry novel pathogenic SOX2 variants. Four cases presented with bilateral anophthalmia in addition to extraocular involvement. Another individual presented with only unilateral anophthalmia. One individual did not have any eye findings but presented with a suprasellar teratoma in infancy and was found to have the recurrent c.70del20 mutation in SOX2 (c.70_89del, p.Asn24Argfs*65). This is this first time this tumor type has been reported in the context of a de novo SOX2 mutation. Notably, individuals with hypothalamic hamartomas and slow-growing hypothalamo-pituitary tumors have been reported previously, but it is still unclear how SOX2 loss contributes to their formation.

Clinical Description, Molecular Analysis of TWIST2 Gene, and Surgical Treatment in a Patient With Barber-Say Syndrome.

Barber-Say syndrome is a rare autosomal dominant disease characterized by dysmorphic features, mainly of the eyelids and skin. It is caused by heterozygous mutations in gene TWIST2, localized in chromosome 2q37.3. The authors present the case of a pediatric patient with a clinical diagnosis of Barber-Say syndrome with ocular symptoms related to exposure keratitis. Molecular analysis of her DNA revealed a mutation on TWIST2 gene confirming the diagnosis of Barber-Say syndrome. Surgical treatment of the patient's eyelids resolved her signs and symptoms.

PAX6 allelic heterogeneity in Mexican congenital aniridia patients: expanding the mutational spectrum with seven novel pathogenic variants.

IMPORTANCE: The importance of the study was to describe the clinical characteristics and mutational analysis of Mexican patients with aniridia. BACKGROUND: Aniridia is a panocular hereditary eye disease caused by mutations in the PAX6 transcription factor. Mutation detection rate is highly variable ranging from 30% to 90% in different populations. Very few studies have been published about the PAX6 mutational analysis in aniridia patients from Mexico. In order to establish a more representative PAX6 mutational frequency in the country, a cohort of 22 Mexican unrelated aniridia probands were analysed in this study. DESIGN: Case series. PARTICIPANTS: A total of 22 Mexican probands with bilateral isolated aniridia and their available relatives were included. METHODS: Sanger sequencing was used for the mutational analysis of all coding exons and flanking intronic regions of PAX6. MAIN OUTCOME MEASURES: Clinical characteristics and results of PAX6 mutational analysis in probands with aniridia and available family members. RESULTS: Molecular analysis of PAX6 in 22 index cases with aniridia allowed the identification of a total of 16 different mutations. Seven of these pathogenic variants are novel, including c.183C>G, p.(Y61*); c.718delC, p.(R240Efs*3); c.1149_1152delTCAG, p.(P385Wfs*139); c.257_266delAAATAGCCCA, p.(K86Sfs*35); c.836_843dupGCAACACA p.(P282Afs*86); c.1032+2_1032+3insT; and c.141+2T>A. Inter and intrafamilial phenotypic heterogeneity was found. CONCLUSIONS AND RELEVANCE: The mutational diagnostic rate in this series was 77%, which is comparable with reports from other populations. Importantly, no founder mutations were identified in this case series. Our results add 7 novel PAX6 pathogenic variants to the aniridia-related mutational spectrum and reveal considerable PAX6 allelic heterogeneity in this population.

[Gene therapy for vision restoration in patients with Leber congenital amaurosis (LCA) due to RPE65 gene mutations: beginning the phase IV trial]. / Terapia génica para la restauración de la visión en pacientes con amaurosis congénita de Leber (LCA) por mutación en el gen RPE65: el inicio de la fase IV.

This is a significant time moment in the field of gene therapy in humans. Recently, results from a phase III clinical trial were published, demonstrating the first gene therapy success for a genetic disease. A clinical trial was carried out in patients suffering a hereditary blindness disease named Leber congenital amaurosis, caused by mutations in the RPE65 gene. Participating subjects received a subretinal injection of the normal RPE65 gene and one year after exhibited a significant improvement in visual acuity. It is expected that this gene therapy treatment will be approved by the FDA and commercialized in the USA in 2017.

Exome sequencing identifies a de novo frameshift mutation in the imprinted gene ZDBF2 in a sporadic patient with Nasopalpebral Lipoma-coloboma syndrome.

Nasopalpebral lipoma-coloboma syndrome (NPLCS, OMIM%167730) is an uncommon malformation entity with autosomal dominant inheritance characterized by the combination of nasopalpebral lipoma, colobomas in upper and lower eyelids, telecanthus, and maxillary hypoplasia. To date, no genetic defects have been associated with familial or sporadic NPLCS cases and the etiology of the disease remains unknown. In this work, the results of whole exome sequencing in a sporadic NPLCS patient are presented. Exome sequencing identified a de novo heterozygous frameshift dinucleotide insertion c.6245_6246 insTT (p.His2082fs*67) in ZDBF2 (zinc finger, DBF-type containing 2), a gene located at 2q33.3. This variant was absent in parental DNA, in a set of 300 ethnically matched controls, and in public exome variant databases. This is the first genetic variant identified in a NPLCS patient and evidence supporting the pathogenicity of the identified mutation is discussed. © 2016 Wiley Periodicals, Inc.

Clinical and Genetic Findings in Mexican Patients with Duane Anomaly and Radial Ray Malformations/Okihiro Syndrome.

BACKGROUND: Okihiro syndrome is an autosomal-dominant condition characterized by radial ray malformations associated with Duane anomaly and other clinical characteristics. SALL4 mutations have been identified in 80-90% of patients with Duane- Radial ray defects/Okihiro syndrome. We report the clinical findings and results of SALL4 sequencing from a group of Mexican patients with this disorder. OBJECTIVE: Clinical description and identification of SALL4 mutations in Mexican subjects with radial defects and Duane anomaly. MATERIALS AND METHODS: Five unrelated index cases were studied. Complete ophthalmologic and general physical examination was performed in all patients. Polymerase chain reaction amplification and automated nucleotide sequencing of coding exons and intron-exon junctions of SALL4 gene were carried out in genomic DNA. RESULTS: A novel heterozygous deletion was identified in one patient. Intragenic heterozygous single nucleotide polymorphisms on SALL4 gene ruled out deletions of some exons in other affected patients in whom non-pathogenic variants were identified by Sanger sequencing. Likewise, multiplex ligation-dependent probe amplification analysis ruled out large deletions in this gene. CONCLUSION: We observed a low frequency of SALL4 mutations in Mexican patients with clinical criteria of Okihiro syndrome.

SOX2 anophthalmia syndrome and dental anomalies.

SOX2 anophthalmia syndrome is an uncommon autosomal dominant syndrome caused by mutations in the SOX2 gene and clinically characterized by severe eye malformations (anophthalmia/microphthalmia) and extraocular anomalies mainly involving brain, esophagus, and genitalia. In this work, a patient with the SOX2 anophthalmia syndrome and exhibiting a novel dental anomaly is described. SOX2 genotyping in this patient revealed an apparently de novo c.70del20 deletion, a commonly reported SOX2 mutation. A review of the phenotypic variation observed in patients carrying the recurrent SOX2 c.70del20 mutation is presented. Although dental anomalies are uncommonly reported in the SOX2 anophthalmia syndrome, we suggest that a dental examination should be performed in patients with SOX2 mutations.

Acro-spondylo-pubic dysostosis associated with cataracts, microcephaly, and normal intelligence.

We report on an adult male with normal intelligence who exhibited an unusual combination of microcephaly, dysostoses of limbs, vertebrae, patellae, and pubic bone, camptodactyly of all fingers, and syndactyly of toes, absent nails on thumbs and some fingers, bilateral cataract, cryptorchidism, polythelia, and nipple-like skin pigmentations of shoulders and upper back. We have been unable to find a description of a similar combination of manifestations in literature. The cause of the anomalies remains unknown.

[Gene therapy for hereditary ophthalmological diseases: Advances and future perspectives]. / Terapia génica para enfermedades hereditarias oftalmológicas: avances y perspectivas.

Gene therapy is a promising new therapeutic strategy that could provide a novel and more effective way of targeting hereditary ophthalmological diseases. The eye is easily accessible, highly compartmentalized, and an immune-privileged organ that gives advantages as an ideal gene therapy target. Recently, important advances in the availability of various intraocular vector delivery routes and viral vectors that are able to efficiently transduce specific ocular cell types have been described. Gene therapy has advanced in some retinal inherited dystrophies; in this way, preliminary success is now being reported for the treatment of Leber congenital amaurosis (LCA). This review will provide an update in the field of gene therapy for the treatment of ocular inherited diseases.