Axenfeld-Rieger syndrome: further clinical and array delineation of four unrelated patients with a 4q25 microdeletion

Genetic changes and testing associated with childhood glaucoma: A systematic review

Many forms of childhood glaucoma have been associated with underlying genetic changes, and variants in many genes have been described. Currently, testing is variable as there are no widely accepted guidelines for testing. This systematic review aimed to summarize the literature describing genetic changes and testing practices in childhood glaucoma. This systematic review was conducted in accordance with the Preferred Reporting Items for Systematic review and Meta-Analyses (PRISMA) 2020 guidelines and registered with Prospero (ID CRD42023400467). A comprehensive review of Pubmed, Embase, and Cochrane databases was performed from inception through March 2, 2023 using the search terms: (glaucoma) AND (pediatric OR childhood OR congenital OR child OR infant OR infantile) AND (gene OR genetic OR genotype OR locus OR genomic OR mutation OR variant OR test OR screen OR panel). Information was extracted regarding genetic variants including genotype-phenotype correlation. Risk of bias was assessed using the Newcastle-Ottawa Scale. Of 1,916 records screened, 196 studies met inclusion criteria and 53 genes were discussed. Among study populations, mean age±SD at glaucoma diagnosis was 8.94±9.54 years and 50.4% were male. The most common gene discussed was CYP1B1, evaluated in 109 (55.6%) studies. CYP1B1 variants were associated with region and population-specific prevalence ranging from 5% to 86% among those with primary congenital glaucoma. MYOC variants were discussed in 31 (15.8%) studies with prevalence up to 36% among patients with juvenile open angle glaucoma. FOXC1 variants were discussed in 25 (12.8%) studies, which demonstrated phenotypic severity dependent on degree of gene expression and type of mutation. Overall risk of bias was low; the most common domains of bias were selection and comparability. Numerous genes and genetic changes have been associated with childhood glaucoma. Understanding the most common genes as well as potential genotype-phenotype correlation has the potential to improve diagnostic and prognostic outcomes for children with glaucoma.

Axenfeld-Rieger syndrome: A systematic review examining genetic, neurological, and neurovascular associations to inform screening

Axenfeld-Rieger Syndrome (ARS) is comprised of a group of autosomal dominant disorders that are each characterized by anterior segment abnormalities of the eye. Mutations in the transcription factors FOXC1 or PITX2 are the most well-studied genetic manifestations of this syndrome. Due to the rarity this syndrome, ARS-associated neurological manifestations have not been well characterized. The purpose of this systematic review is to characterize and describe ARS neurologic manifestations that affect the cerebral vasculature and their early and late sequelae. PRISMA guidelines were followed; studies meeting inclusion criteria were analyzed for study design, evidence level, number of patients, patient age, whether the patients were related, genotype, ocular findings, and nervous system findings, specifically neurostructural and neurovascular manifestations. 63 studies met inclusion criteria, 60 (95%) were case studies or case series. The FOXC1 gene was most commonly found, followed by COL4A1, then PITX2. The most commonly described structural neurological findings were white matter abnormalities in 26 (41.3%) of studies, followed by Dandy-Walker Complex 12 (19%), and agenesis of the corpus callosum 11 (17%). Neurovascular findings were examined in 6 (9%) of studies, identifying stroke, cerebral small vessel disease (CSVD), tortuosity/dolichoectasia of arteries, among others, with no mention of moyamoya. This is the first systematic review investigating the genetic, neurological, and neurovascular associations with ARS. Structural neurological manifestations were common, yet often benign, perhaps limiting the utility of MRI screening. Neurovascular abnormalities, specifically stroke and CSVD, were identified in this population. Stroke risk was present in the presence and absence of cardiac comorbidities. These findings suggest a relationship between ARS and neurovascular findings; however, larger scale studies are necessary inform therapeutic decisions.

4q25 Microdeletion with Axenfeld-Rieger Syndrome and Developmental Delay

We encountered a case with congenital iris coloboma, omphalocele, and developmental delay with a 2.5 Mb deletion on chromosome 4q25 encompassing PITX2, leading to Axenfeld-Rieger syndrome (ARS), NEUROG2, and ANK2. ARS is characterized by the aplasia of the anterior eye, odontogenesis, and abdominal wall aplasia. In our case, iris coloboma and omphalocele were thought to be caused by PITX2 haploinsufficiency. However, these symptoms are nonspecific, and clinical symptoms alone can make it difficult to make a correct diagnosis. In addition, the genes responsible for developmental delay, among others, are not well understood. Developmental delay, in this case, might be caused due to NEUROG2 haploinsufficiency. In spite of the partial deletion of ANK2, the causative gene of long QT syndrome type 4, the electrocardiogram was normal. Genetic testing can lead to a correct diagnosis, and it may be effective in detecting complications.

Axenfeld-Rieger syndrome combined with a foveal anomaly in a three-generation family: a case report

Background

Axenfeld-Rieger syndrome (ARS) is a rare autosomal dominant eye disorder that can also affect other organs of the human body. The condition is primarily characterized by the anterior segmental abnormalities of the eye. Here, we present an observational case series of a three-generation family with ARS and unexpected foveal anomaly.

Case presentation

A 33-year-old woman was admitted to an Ophthalmology Clinic in Bialystok for left eye congenital cataract surgery. The patient (proband) was diagnosed with visual deterioration, multiple defects of iris, corectopia, displacement of the Schwalbe’s line, and phenotypic characteristics of ARS. A perimetric examination indicated peripheral visual field loss and signs typical for glaucoma. Based on the phenotypic symptoms and genetic test, the patient was diagnosed with Axenfeld Rieger Syndrome. However, the optical coherence tomography of the macula showed foveal anomaly (absence of the physiological pit), which is not typically associated with this genetic disorder. The patient’s family history revealed that her two daughters were undergoing treatment for congenital glaucoma, and one of the daughters also had foveal anomaly the same as her mother. Interestingly, an examination of the patient’s mother showed typical phenotypic features of ARS such as a defect of the iris, posterior embryotoxon, and coloboma, as well as foveal anomaly. A genetic test confirmed PITX2 mutation in both, proband’s two daughters and mother.

Conclusions

This study highlights the occurrence of ARS with unusual ophthalmic features such as foveal anomaly (absence of the physiological pit) in a three-generation family. Although ARS is known to represent the developmental defects of the anterior segment of the eye, it is very important to perform fundus evaluation to identify associated posterior segment anomalies that may affect visual acuity. The presence of ocular defects not typically associated with ARS suggests a wide spectrum of mutations within PITX2 gene which are required to identify in order to determine genotype- phenotype correlation in ARS affected individuals.

Novel mutations in the PITX2 gene in Pakistani and Mexican families with Axenfeld-Rieger syndrome

PURPOSE

Axenfeld-Rieger syndrome (ARS) is a rare autosomal dominant disorder that affects the anterior segment of the eye. The aim of this study was to examine the PITX2 gene to identify possible novel mutations in Pakistani and Mexican families affected by the ARS phenotype.

METHODS

Three unrelated probands with a diagnosis of ARS were recruited for this study. Genomic DNA was isolated from the peripheral blood of the probands and their family members. Polymerase chain reaction and Sanger sequencing were used for the analysis of coding exons and the flanking intronic regions of the PITX2 gene. Bioinformatics tools and database (VarSome, Provean, and MutationTaster, SIFT, PolyPhen-2, and HOPE) were evaluated to explore missense variants.

RESULTS

We identified novel heterozygous variations in the PITX2 gene that segregated with the ARS phenotype within the families. The variant NM_153426.2(PITX2):c.226G > T or p.(Ala76Ser) and the mutation NM_153426.2(PITX2):c.455G > A or p.(Cys152Tyr) were identified in two Pakistani pedigrees, and the mutation NM_153426.2(PITX2):c.242_265del or p.(Lys81_Gln88del), segregated in a Mexican family.

CONCLUSION

Our study extends the spectrum of PITX2 mutations in individuals with ARS, enabling an improved diagnosis of this rare but serious syndrome.

Axenfeld-Rieger Syndrome: Rare Case Presentation and Overview

Axenfeld-Rieger syndrome (ARS) is an extremely rare autosomal dominant disorder characterized by ocular, craniofacial, dental and periumbilical abnormalities. We present a case of a 10-year-old boy. Its awareness among oral surgeons is essential for timely diagnosis and subsequent prevention of ophthalmic and systemic complications as craniofacial and dental features constitute the early recognizable symptoms of this syndrome. Systematic ophthalmic surgeries aid in relieving vision abnormalities, while symptomatic dental treatment should be provided for masticatory and esthetic rehabilitation.

A novel 4q25 microdeletion encompassing PITX2 associated with Rieger syndrome

OBJECTIVE

Rieger syndrome (RS) is a genetic disorder characterized by abnormal development of the eyes, teeth, and umbilicus, and the paired-like homeodomain 2 (PITX2) gene is often implicated in its pathogenesis. This study aimed to identify the underlying genetic defect in a Chinese patient with RS.

SUBJECTS AND METHODS

DNA samples were screened for PITX2 gene mutations and copy number variations (CNVs) using Sanger sequencing and genomic quantitative PCR analysis (qPCR). Chromosomal microarray analysis (CMA) was performed to fine-map the CNVs.

RESULTS

The proband suffered from severe hypodontia and conical teeth in her permanent dentition. No PITX2 point mutations were found in this Chinese family, but a heterozygous deletion involving PITX2 was suspected and verified by the SNPs analysis and qPCR in the proband. An approximately 0.47 Mb (chr4: 111, 334, 313-111, 799, 327, GRCh37/hg19) deletion including PITX2 was finally determined by CMA.

CONCLUSIONS

To our knowledge, this is the first reported case of RS caused by a CNV of the PITX2 gene in a Chinese patient. CNV screening must be considered if point mutation screens yield negative results in these patients. The distribution of SNP genotypes among family members may also provide clues about gene deletion.

Corneal endothelial cell density and cardiovascular mortality: A Global Survey and Correlative Meta-Analysis

Based on embryological commonalities between eye and heart development, a global, country-specific meta-analysis of normal, adult corneal endothelial cell density (ECD) was performed and correlated against mortality rates secondary to diseases affecting cardiac neural crest cell (CNCC)-derived cardiovascular structures. A country-specific survey of ECD was performed by searching PubMed for studies reporting ECD datasets from normal adults. All eligible datasets were assigned a country of origin. Country-specific weighted mean ECD were calculated based on dataset n. Country-specific disease mortality rates were obtained from the World Health Organization. The correlations between weighted mean ECD and mortality rates secondary to diseases affecting CNCC-derived cardiovascular structures were calculated. As controls, correlations between ECD and noncardiovascular disease mortality were examined. Pearson correlation coefficients (r) corresponding to P-value < 0.05 were considered significant. Three hundred ninety-two datasets (39,762 eyes) from 267 source-studies were assigned to 42 countries. Significant correlations were found between ECD and mortality due to coronary heart disease (r = -0.39, P = 0.011), hypertension (r = -0.33, P = 0.033), and all-cause cardiac disease (r = -0.36, P = 0.019). No significant correlations were found between ECD and mortality secondary to the control conditions: inflammatory heart disease (mesoderm-derived tissues) (r = -0.12, P = 0.45), diabetes (r = -0.13, P = 0.41), lung disease (r = -0.21, P = 0.18), liver disease (r = -0.13, P = 0.41), renal disease (r = -0.10, P = 0.53), lung cancer (r = 0.02, P = 0.90), pancreatic cancer (r = 0.24, P = 0.13), malnutrition (r = -0.07, P = 0.66), or all-cause mortality (r = 0.04, P = 0.81). Negative correlations exist between ECD and mortality due to coronary artery disease and hypertension. On a population-based level, adult ECD is correlated to mortality from certain cardiovascular diseases. Clin. Anat. 31:927-936, 2018. © 2018 Wiley Periodicals, Inc.

4q25 microdeletion encompassing PITX2: A patient presenting with tetralogy of Fallot and dental anomalies without ocular features

Axenfeld-Rieger syndrome (ARS) is a heterogeneous clinical entity transmitted in an autosomal dominant manner. The main feature, Axenfeld-Rieger Anomaly (ARA), is a malformation of the anterior segment of the eye that can lead to glaucoma and impair vision. Extra-ocular defects have also been reported. Point mutations of FOXC1 and PITX2 are responsible for about 40% of the ARS cases. We describe the phenotype of a patient carrying a deletion encompassing the 4q25 locus containing PITX2 gene. This child presented with a congenital heart defect (Tetralogy of Fallot, TOF) and no signs of ARA. He is the first patient described with TOF and a complete deletion of PITX2 (arr[GRCh37]4q25(110843057-112077858)x1, involving PITX2, EGF, ELOVL6 and ENPEP) inherited from his ARS affected mother. In addition, to our knowledge, he is the first patient reported with no ocular phenotype associated with haploinsufficiency of PITX2. We compare the phenotype and genotype of this patient to those of five other patients carrying 4q25 deletions. Two of these patients were enrolled in the university hospital in Toulouse, while the other three were already documented in DECIPHER. This comparative study suggests both an incomplete penetrance of the ocular malformation pattern in patients carrying PITX2 deletions and a putative association between TOF and PITX2 haploinsufficiency.

The rare Axenfeld-Rieger syndrome with systemic anomalies: A case report and brief review of literature

RATIONALE

Axenfeld-Rieger syndrome (ARS) is a rare autosomal dominant disorder with ocular anterior segment dysgenesis and systemic anomalies.

PATIENT CONCERNS

A 28-year-old Chinese Han female was referred to Beijing Tongren Eye Center for progressive decrease of the visual acuity on her right eye in the past month.

DIAGNOSES

The patient was diagnosed as ARS with retinal detachment based on series of ophthalmic examinations performed.

INTERVENTIONS

A pars plana vitrectomy was performed to manage the retinal detachment.

OUTCOMES

Her best-corrected visual acuity was slightly improved after surgery.

LESSONS

ARS is a developmental defect of ocular anterior segment with various clinical manifestations which might cause misdiagnosis.

Angiopoietin receptor TEK mutations underlie primary congenital glaucoma with variable expressivity

Primary congenital glaucoma (PCG) is a devastating eye disease and an important cause of childhood blindness worldwide. In PCG, defects in the anterior chamber aqueous humor outflow structures of the eye result in elevated intraocular pressure (IOP); however, the genes and molecular mechanisms involved in the etiology of these defects have not been fully characterized. Previously, we observed PCG-like phenotypes in transgenic mice that lack functional angiopoietin-TEK signaling. Herein, we identified rare TEK variants in 10 of 189 unrelated PCG families and demonstrated that each mutation results in haploinsufficiency due to protein loss of function. Multiple cellular mechanisms were responsible for the loss of protein function resulting from individual TEK variants, including an absence of normal protein production, protein aggregate formation, enhanced proteasomal degradation, altered subcellular localization, and reduced responsiveness to ligand stimulation. Further, in mice, hemizygosity for Tek led to the formation of severely hypomorphic Schlemm's canal and trabecular meshwork, as well as elevated IOP, demonstrating that anterior chamber vascular development is sensitive to Tek gene dosage and the resulting decrease in angiopoietin-TEK signaling. Collectively, these results identify TEK mutations in patients with PCG that likely underlie disease and are transmitted in an autosomal dominant pattern with variable expressivity.