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.

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.

Genetic Aspects of Glaucoma: An Updated Review.

Glaucoma is a group of diverse diseases characterized by cupping of the optic nerve head due to the loss of retinal ganglion cells. It is the most common cause of irreversible blindness throughout the word; therefore, its timely diagnosis and early detection through an ophthalmological examination are very important. We, herein, present the information on the epidemiology, pathophysiology, clinical diagnosis, and treatment of glaucoma. We also emphasize the investigations of the last decades that have allowed identifying numerous genes and susceptible genetic factors. We have also described in detail the genes whose mutations cause or contribute to the development of the disease.

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.

Familial Hypercholesterolemia: Update and Review.

Knowledge of epidemiology, genetic etiopathogenesis, diagnostic criteria, and management of familial hypercholesterolemia have increased in the last two decades. Several population studies have shown that familial hypercholesterolemia is more frequent than previously thought, making this entity the most common metabolic disease with monogenic inheritance in the world. Identification of causal heterozygous pathogenic variants in LDLR, APOB, and PCSK9 genes has increased diagnostic accuracy of classical criteria (extreme hypercholesterolemia, personal / family history of premature coronary artery disease or other cardiovascular diseases). Genetic screening has been recently introduced in many European countries to detect patients with familial hypercholesterolemia, mainly affected pediatric subjects, asymptomatic or those at the beggining of their disease, to increase surveillance and avoid complications such as cardiovascular diseases. Cholesterol- lowering drugs should be started as soon as the diagnosis is made. Various combinations between drugs can be used when the goal is not achieved. New therapies, including small interference ribonucleic acids (siRNA) are being tested in different clinical trials.

CYP1B1 Cytopathy: Uncommon Phenotype of a Homozygous CYP1B1 Deletion as Internal Corneal Ulcer of Von Hippel.

PURPOSE: To report a mutation of CYP1B1 in a newborn with a rare phenotype without the classic features of anterior segment dysgenesis or congenital glaucoma. METHODS: The newborn presented with diffuse corneal edema and bilaterally elevated intraocular pressure (IOP). Ophthalmological examination, ultrasound, and ultrasound biomicroscopy were performed; congenital infections were ruled out. Genetic analysis was performed. The patient underwent penetrating keratoplasty and goniotomy in a single surgical time. The button was subjected to histopathological examination. RESULTS: The patient is the first child of young, healthy, consanguineous parents. Ophthalmological examination revealed visual acuity of light perception and increased IOP in both eyes. CYP1B1 gene analysis demonstrated homozygosity for a 1-bp deletion in exon 2 (c.830delT). IOP was normalized, and the corneal button was clear after surgical treatment. Histopathological analysis revealed loss of the Bowman membrane in the central cornea, fibrosis of the stroma, absence of endothelial cells, and loss of Descemet membrane centrally. CONCLUSIONS: We present an uncommon mutation and clinical description of CYP1B1. This report and further studies could provide us better understanding of the mutational spectrum of CYP1B1.

[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.

A rapidly progressive defective spermatogenesis in a Mexican family affected by spino-bulbar muscular atrophy.

Spino-bulbar muscular atrophy (SBMA) is an X-linked recessive adult progressive disorder affecting motor neurons. It is caused by a poly-glutamine tract expansion in the androgen receptor (AR) which generates protein aggregates that cannot be processed by proteasomes. A secondary mild androgen resistance is developed by AR dysfunction and patients present endocrine abnormalities including gynecomastia and poor function of testosterone in tissues; however, normally they are fertile. In this report we describe a Mexican family with three affected brothers with primary infertility caused by a progressive impairment of spermatogenesis leading to azoospermia before 40 years of age. They presented common features associated to patients affected by SMBA, such as gynecomastia, high level of CPK, muscle cramps, fasciculations, muscle wastage, and impaired swallowing. Two intracytoplasmic sperm injection (ICSI) cycles were performed in one of the patients resulting in fertilization failure. Molecular analysis of AR gene exon 1 revealed 54 CAG repeats in DNA extracted from leukocytes in affected patients and 22 repeats in the fertile non-affected brother. Severe impaired spermatogenesis of rapid progression has not been associated before to SBMA. This is the first report of assisted reproduction techniques indicated by male infertility in patients with this rare disorder. Further studies are required to confirm the unusual result of intracytoplasmic sperm injection cycles. We discuss the implications and possible pathogenesis of these unique features of SBMA in this family.

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.

[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.

Review and update on the molecular basis of Leber congenital amaurosis.

Inherited retinal diseases are uncommon pathologies and one of the most harmful causes of childhood and adult blindness. Leber congenital amaurosis (LCA) is the most severe kind of these diseases accounting for approximately 5% of the whole retinal dystrophies and 20% of the children that study on blind schools. Clinical ophthalmologic findings including severe vision loss, nystagmus and ERG abnormalities should be suspected through the first year of life in this group of patients. Phenotypic variability is found when LCA patients have a full ophthalmologic examination. However, a correct diagnosis may be carried out; the determination of ophthalmologic clues as light sensibility, night blindness, fundus pigmentation, among other, join with electroretinographics findings, optical coherence tomography, and new technologies as molecular gene testing may help to reach to a precise diagnosis. Several retinal clinical features in LCA may suggest a genetic or gene particular defect; thus genetic-molecular tools could directly corroborate the clinical diagnosis. Currently, approximately 20 genes have been associated to LCA. In this review, historical perspective, clinical ophthalmological findings, new molecular-genetics technologies, possible phenotype-genotypes correlations, and gene therapy for some LCA genes are described.

[Prenatal exclusion of von Hippel-Lindau syndrome in a Mexican family carrying a novel VHL gene mutation]. / Exclusión prenatal del síndrome de von Hippel-Lindau en una familia Mexicana con una mutación nueva en el gen VHL.

BACKGROUND: von Hippel-Lindau (VHL) disease is an autosomal dominant and familial multisystemic syndrome that is caused by the inactivation of the VHL gene and it is characterized by diverse types of high vasculated tumours of benign and malign nature. In this work we describe the clinical characteristics and the prenatal diagnosis of a woman with VHL. OBJECTIVE: Describe the first exclusion prenatal case by DNA analysis of the VHL syndrome in Latinoamerican population. MATERIAL AND METHODS: Analysis of a Mexican familial pedigree showed 5 affected subjects with VHL on 3 consecutive generations. The proband was a 7 weeks pregnancy woman who was referred to our service for familiar and personal history of this disease. Maternal DNA was obtained from peripheral blood leukocytes, while fetal DNA was isolated from amniotic liquid cells on the 15th week. The maternal and fetal DNA analysis were done by the Polymerase Chain reaction (PCR) and the direct nucleotide sequence of the VHL gene. RESULTS: A novel mutation (c. 161_168 dup GGAGGCCG) in the VHL gene was identified in maternal DNA. Fetal DNA analysis indicated that the fetus inherited the wild-type allele from the mother. CONCLUSION: A novel VHL gene mutation was identified in a familial case of the disease, expanding the mutational spectrum in this disorder. The molecular prenatal testing in the affected woman at 15 weeks of gestation, demonstrated that the fetus did nor inherited the mutated allele. To the best of our knowledge, this is the first example of prenatal-molecular exclusion on VHL syndrome in Latinoamerica population.

[Prenatal exclusion of von Hippel-Lindau syndrome in a Mexican family carrying a novel VHL gene mutation]. / Exclusión prenatal del sindrome de von Hippel-Lindau en una familia Mexicana con una mutación nueva en el gen VHL.

Von Hippel-Lindau syndrome is an autosomal dominant and familial multisystemic syndrome that is caused by the inactivation of the VHL gene and it is characterized by diverse types of high vasculated tumors of benign and malign nature. This paper reports the clinical characteristics and prenatal diagnosis of a woman with von Hippel-Lindau syndrome, who constitutes the first exclusion prenatal case by DNA analysis of the Von Hippel-Lindau syndrome in Latin-American population.