Sclerocornea associated with the chromosome 22q11.2 deletion syndrome

Multiple congenital ocular anomalies in three related litters of Jack Russell Terrier puppies

OBJECTIVE

To describe multiple congenital ocular anomalies in three litters of Jack Russell Terrier puppies.

ANIMALS STUDIED

Seven purebred Jack Russell Terrier puppies from three related litters and their four parents.

PROCEDURES

Medical records of the puppies and their parents were evaluated. All dogs underwent a complete ophthalmic examination, followed by bilateral ocular ultrasonography in two of the puppies with complete corneal opacity. One eye from an affected puppy was subjected to histopathology. A complete database of pedigrees was built, and individual inbreeding was evaluated.

RESULTS

The most commonly diagnosed ocular anomalies in the puppies were: various anomalies of the fundus (12/14 eyes); microphthalmia (10/14 eyes); sclerocornea (8/14 eyes); and persistent pupillary membranes (7/14 eyes). Six out of seven puppies had at least two ocular abnormalities, and only one puppy was normal. Four out of seven puppies had sclerocornea, a particular corneal opacity to date described only in Spanish Podenco dogs. No ocular abnormalities were found in the parents examined (4/4). Analysis of the pedigrees showed that all the puppies and two parents were inbred, and the individual values of the inbreeding puppies were greater than 6.25% in two litters.

CONCLUSIONS

Inbreeding with closely related Jack Russell Terriers may result in severe congenital eye abnormalities in puppies.

Congenital anterior segment ocular disorders: Genotype-phenotype correlations and emerging novel mechanisms

Development of the anterior segment of the eye requires reciprocal sequential interactions between the arising tissues, facilitated by numerous genetic factors. Disruption of any of these processes results in congenital anomalies in the affected tissue(s) leading to anterior segment disorders (ASD) including aniridia, Axenfeld-Rieger anomaly, congenital corneal opacities (Peters anomaly, cornea plana, congenital primary aphakia), and primary congenital glaucoma. Current understanding of the genetic factors involved in ASD remains incomplete, with approximately 50% overall receiving a genetic diagnosis. While some genes are strongly associated with a specific clinical diagnosis, the majority of known factors are linked with highly variable phenotypic presentations, with pathogenic variants in FOXC1, CYP1B1, and PITX2 associated with the broadest spectrum of ASD conditions. This review discusses typical clinical presentations including associated systemic features of various forms of ASD; the latest functional data and genotype-phenotype correlations related to 25 ASD factors including newly identified genes; promising novel candidates; and current and emerging treatments for these complex conditions. Recent developments of interest in the genetics of ASD include identification of phenotypic expansions for several factors, discovery of multiple modes of inheritance for some genes, and novel mechanisms including a growing number of non-coding variants and alleles affecting specific domains/residues and requiring further studies.

The Co-Occurrence of 22q11.2 Deletion Syndrome and Epithelial Basement Membrane Dystrophy: A Case Report and Review of the Literature

BACKGROUND

22q11.2 deletion syndrome (22q11.2DS) is a genetic disorder caused by the deletion of the q11.2 band of chromosome 22. It may affect various systems, including the cardiovascular, immunological, gastrointestinal, endocrine, and neurocognitive systems. Additionally, several ocular manifestations have been described.

RESULTS

We report a case of a 34-year-old female diagnosed with 22q11.2DS who presented with visual discomfort and foreign body sensation in both eyes. She had no history of recurrent ocular pain. A comprehensive ophthalmological examination was performed, including anterior segment optical coherence tomography and in vivo confocal microscopy. Overall, the exams revealed bilateral corneal map-like lines, dots, and fingerprint patterns, consistent with a diagnosis of epithelial basement membrane dystrophy (EBMD). In addition to presenting with this novel corneal manifestation for 22q11.2 DS, we review the ocular clinical features of 22q11.2DS in the context of our case.

CONCLUSIONS

The EBMD may represent a new corneal manifestation associated with 22q11.2 syndrome, although the link between these conditions is unknown. Further research is warranted to investigate potentially shared genetic or molecular pathways to the understanding of the phenotypic variety observed among this rare syndrome.

Overview of sclerocornea

Sclerocornea is a rare non-progressive, non-inflammatory usually bilateral congenital corneal opacity that can be associated with both ocular and systemic abnormalities. It could be inherited in 50% of cases. Ill-defined limbal architecture and vascularization in association with ocular comorbidities results in poor outcomes with corneal transplantation. This narrative review summarizes the current literature on etiology and clinical presentation in sclerocornea. With regards to keratoplasty, it focusses on key elements in decision making, highlights the role of investigations and discusses practical surgical pearls to enhance outcome of keratoplasty in these eyes.

Congenital Corneal Opacity in 22q11.2 Deletion Syndrome: A Case Series

PURPOSE

The purpose of this study was to describe the deep phenotype of congenital corneal opacities (CCO) in patients with 22q11.2 deletion syndrome (22q11.2 DS) and to identify putative regions or genes that could explain the CCO.

METHODS

A retrospective chart review was conducted to identify patients with 22q11.2 DS seen in the ophthalmology clinic of a tertiary referral children's hospital. Thirty patients were identified, with molecular confirmation. Twenty-six did not show structural anterior segment anomalies aside from posterior embryotoxon (n = 4), whereas 4 had bilateral CCO, of which 3 had preoperative images. We reviewed medical, operative, and pathology reports; anterior segment optical coherence tomography; high-frequency ultrasound; histopathologic slides; and genetic testing. To identify putative genes responsible for CCO, chromosomal breakpoints in patients with and without CCO were compared.

RESULTS

In the 3 patients with preoperative imaging and CCO, a pattern of paracentral corneal opacification with central clearing accompanied by iridocorneal or keratolenticular adhesions was observed. Anterior segment optical coherence tomography and histopathologic images showed central stromal thinning with a residual structure consistent with Descemet membrane. One patient presented at birth with unilateral corneal perforation, suggestive of likely stromal thinning. A comparison of the breakpoints across all cases failed to reveal unique regions or genes in patients with CCO.

CONCLUSIONS

22q11.2 DS can rarely be associated with CCO. We describe a consistent pattern of central clearing related to posterior stromal thinning, with or without ICA/KLA. Possible candidate genes for corneal opacification in 22q11.2 DS remain elusive.

Updated clinical practice recommendations for managing children with 22q11.2 deletion syndrome

This review aimed to update the clinical practice guidelines for managing children and adolescents with 22q11.2 deletion syndrome (22q11.2DS). The 22q11.2 Society, the international scientific organization studying chromosome 22q11.2 differences and related conditions, recruited expert clinicians worldwide to revise the original 2011 pediatric clinical practice guidelines in a stepwise process: (1) a systematic literature search (1992-2021), (2) study selection and data extraction by clinical experts from 9 different countries, covering 24 subspecialties, and (3) creation of a draft consensus document based on the literature and expert opinion, which was further shaped by survey results from family support organizations regarding perceived needs. Of 2441 22q11.2DS-relevant publications initially identified, 2344 received full-text reviews, including 1545 meeting criteria for potential relevance to clinical care of children and adolescents. Informed by the available literature, recommendations were formulated. Given evidence base limitations, multidisciplinary recommendations represent consensus statements of good practice for this evolving field. These recommendations provide contemporary guidance for evaluation, surveillance, and management of the many 22q11.2DS-associated physical, cognitive, behavioral, and psychiatric morbidities while addressing important genetic counseling and psychosocial issues.

Clinical Manifestations of 22q11.2 Deletion Syndrome

DiGeorge syndrome (DGS), also known as "22q11.2 deletion syndrome" (22q11DS) (MIM # 192430 # 188400), is a genetic disorder caused by hemizygous microdeletion of the long arm of chromosome 22. In the last decades, the introduction of fluorescence in situ hybridization assays, and in selected cases the use of multiplex ligation-dependent probe amplification, has allowed the detection of chromosomal microdeletions that could not be previously identified using standard karyotype analysis. The aim of this review is to address cardiovascular and systemic involvement in children with DGS, provide genotype-phenotype correlations, and discuss their medical management and therapeutic options.

Atypical presentation of Cat Eye Syndrome in an infant with Peters anomaly and microphthalmia with cyst

PURPOSE

To describe a unique ocular presentation of Cat Eye Syndrome and review the ocular and systemic findings associated with the syndrome.

METHODS

Case report with multimodal imaging.

RESULTS

A newborn female presented with a unilateral Peters anomaly with contralateral microphthalmia with cyst. The patient's other systemic findings included a hypoplastic right heart, persistent ductus arteriosus, intrauterine growth retardation, bilateral anotia, preauricular ear pits and skin tags, micrognathia, hypoplastic female genitalia, and unilateral cranial nerve VII palsy. Chromosomal microarray testing showed tetrasomy of chromosome 22 in the q11.1-q11.21 region consistent with Cat Eye Syndrome. The patient ultimately underwent a successful optical iridectomy on one side and orbitotomy with excision of the cystic mass on the other.

CONCLUSIONS

The co-occurrence of unilateral Peters anomaly with contralateral microphthalmia with cyst in Cat Eye Syndrome is rare and demonstrative of the syndrome's phenotypic variability. The medical and surgical management of these patients may require a multidisciplinary approach and must be tailored to the individual findings and overall systemic health of the patient.

What is new with 22q? An update from the 22q and You Center at the Children's Hospital of Philadelphia

22q11.2 deletion syndrome (22q11.2DS) is a disorder caused by recurrent, chromosome-specific, low copy repeat (LCR)-mediated copy-number losses of chromosome 22q11. The Children's Hospital of Philadelphia has been involved in the clinical care of individuals with what is now known as 22q11.2DS since our initial report of the association with DiGeorge syndrome in 1982. We reviewed the medical records on our continuously growing longitudinal cohort of 1,421 patients with molecularly confirmed 22q11.2DS from 1992 to 2018. Most individuals are Caucasian and older than 8 years. The mean age at diagnosis was 3.9 years. The majority of patients (85%) had typical LCR22A-LCR22D deletions, and only 7% of these typical deletions were inherited from a parent harboring the deletion constitutionally. However, 6% of individuals harbored other nested deletions that would not be identified by traditional 22q11.2 FISH, thus requiring an orthogonal technology to diagnose. Major medical problems included immune dysfunction or allergies (77%), palatal abnormalities (67%), congenital heart disease (64%), gastrointestinal difficulties (65%), endocrine dysfunction (>50%), scoliosis (50%), renal anomalies (16%), and airway abnormalities. Median full-scale intelligence quotient was 76, with no significant difference between individuals with and without congenital heart disease or hypocalcemia. Characteristic dysmorphic facial features were present in most individuals, but dermatoglyphic patterns of our cohort are similar to normal controls. This is the largest longitudinal study of patients with 22q11.2DS, helping to further describe the condition and aid in diagnosis and management. Further surveillance will likely elucidate additional clinically relevant findings as they age.

A Novel Mutation of KIF11 in a Child with 22q11.2 Deletion Syndrome Associated with MCLMR

Microcephaly with or without chorioretinopathy, lymphedema, or mental retardation (MCLMR; OMIM 152950) is a rare autosomal dominantly inherited syndrome. Mutations in the kinesin family member 11 (KIF11) gene have been associated with this condition. Here, we report a de novo novel heterozygous missense mutation in exon 12 of the KIF11 gene [c.1402T>G; p.(Leu468Val)] in a boy with 22q11.2 microdeletion syndrome. His major features were microcephaly, ventricular septal defect, congenital lymphedema of the feet, and distinct facial appearance including upslanting palpebral fissures, a broad nose with rounded tip, anteverted nares, long philtrum with a thin upper lip, pointed chin, and prominent ears. His right eye was enucleated due to subretinal hemorrhage and retinal detachment at age 3 months. Lacunae of chorioretinal atrophy and the pale optic disc were present in the left eye. He also had a de novo 1.6-Mb microdeletion in the Di George/VCFS region of chromosome 22q11.2 in SNP array, which was confirmed by FISH analysis. In this study, for the first time, we describe the co-occurrence of a KIF11 mutation and 22q11.2 deletion syndrome in a patient with MCLMR.

Ocular Findings in Children With 22q11.2 Deletion Syndrome

PURPOSE

To identify the ocular features of children diagnosed as having 22q11.2 deletion syndrome in a Turkish population, which is the most common microdeletion syndrome with a wide range of facial and ocular abnormalities.

METHODS

Sixteen children aged between 4 months and 18 years with a microdeletion in chromosome 22q11.2 underwent a detailed ophthalmological examination including uncorrected and best corrected visual acuity testing, stereoscopic vision examination, biomicroscopic and indirect fundus examination, and ocular motility testing.

RESULTS

All patients had at least one ocular abnormality. The major abnormalities were eyelid abnormalities (eye hooding, narrow palpebral fissure, telecanthus, hypertelorism, sparse and thin eyebrows and eyelashes, blepharitis, and distichiasis), posterior embryotoxon, and tortuous retinal vessels in at least half of the patients. Other ophthalmological disorders were refractive errors, iris remnants, and strabismus.

CONCLUSIONS

The chromosome 22q11.2 deletion syndrome is associated with a wide range of ocular disorders, which necessitates a comprehensive eye examination for appropriate treatment and follow-up. Ocular findings sometimes can provide a clue to the diagnosis of 22q11.2 deletion. [J Pediatr Ophthalmol Strabismus. 2016;53(4):218-222].

Ocular findings associated with chromosome 22q11.2 duplication

We describe the ocular features of the chromosome 22q11.2 duplication syndrome and provide ophthalmologic examination recommendations for affected patients. The medical records of 19 children with chromosome 22q11.2 duplication who had undergone complete ophthalmological examination, including dilated fundus examination and cycloplegic refraction, were studied retrospectively. Over half of the children with 22q11.2 duplication syndrome were found to have visually significant ocular abnormalities, including 6 with strabismus, 2 with moderately high astigmatism requiring glasses, 1 with unilateral congenital cataract requiring surgery, 1 with optic disk drusen, 1 with bilateral megalocornea with normal eye pressures, 1 with nystagmus that resolved spontaneously, and 1 with delayed visual maturation. Because of the high incidence of conditions that could affect visual development, we recommend that children with 22q11.2 duplication syndrome have a complete ophthalmological examination on diagnosis and regular vision screenings by their primary care physician thereafter.

22q11.2 deletion syndrome

22q11.2 deletion syndrome (22q11.2DS) is the most common chromosomal microdeletion disorder, estimated to result mainly from de novo non-homologous meiotic recombination events occurring in approximately 1 in every 1,000 fetuses. The first description in the English language of the constellation of findings now known to be due to this chromosomal difference was made in the 1960s in children with DiGeorge syndrome, who presented with the clinical triad of immunodeficiency, hypoparathyroidism and congenital heart disease. The syndrome is now known to have a heterogeneous presentation that includes multiple additional congenital anomalies and later-onset conditions, such as palatal, gastrointestinal and renal abnormalities, autoimmune disease, variable cognitive delays, behavioural phenotypes and psychiatric illness - all far extending the original description of DiGeorge syndrome. Management requires a multidisciplinary approach involving paediatrics, general medicine, surgery, psychiatry, psychology, interventional therapies (physical, occupational, speech, language and behavioural) and genetic counselling. Although common, lack of recognition of the condition and/or lack of familiarity with genetic testing methods, together with the wide variability of clinical presentation, delays diagnosis. Early diagnosis, preferably prenatally or neonatally, could improve outcomes, thus stressing the importance of universal screening. Equally important, 22q11.2DS has become a model for understanding rare and frequent congenital anomalies, medical conditions, psychiatric and developmental disorders, and may provide a platform to better understand these disorders while affording opportunities for translational strategies across the lifespan for both patients with 22q11.2DS and those with these associated features in the general population.

Sclerocornea in a patient with van den Ende-Gupta syndrome homozygous for a SCARF2 microdeletion

Van den Ende-Gupta Syndrome (VDEGS) is an autosomal recessive disorder characterized by blepharophimosis, distinctive nose, hypoplastic maxilla, and skeletal abnormalities. Using homozygosity mapping in four VDEGS patients from three consanguineous families, Anastacio et al. [Anastacio et al. (2010); Am J Hum Genet 87:553-559] identified homozygous mutations in SCARF2, located at 22q11.2. Bedeschi et al. [2010] described a VDEGS patient with sclerocornea and cataracts with compound heterozygosity for the common 22q11.2 microdeletion and a hemizygous SCARF2 mutation. Because sclerocornea had been described in DiGeorge-velo-cardio-facial syndrome but not in VDEGS, they suggested that the ocular abnormalities were caused by the 22q11.2 microdeletion. We report on a 23-year-old male who presented with bilateral sclerocornea and the VDGEGS phenotype who was subsequently found to be homozygous for a 17 bp deletion in exon 4 of SCARF2. The occurrence of bilateral sclerocornea in our patient together with that of Bedeschi et al., suggests that the full VDEGS phenotype may include sclerocornea resulting from homozygosity or compound heterozygosity for loss of function variants in SCARF2.

A case of 22q11.2 deletion syndrome with Peters anomaly, congenital glaucoma, and heterozygous mutation in CYP1B1

We read with interest the recent publication by Tarlan and colleagues 1 describing a patient with 22q11.2 deletion syndrome and ocular features of right microphthalmia and left anterior segment dysgenesis. While anterior segment dysgenesis disorders are occasionally reported with 22q11.2 deletions, 2-5 this remains a rare association. We report here an 8-year-old patient with 22q11.2 deletion syndrome and bilateral Peters anomaly with congenital glaucoma; in addition, our patient was found to have a single heterozygous mutation in CYP1B1, c.83C > T, p.(Ser28Trp).

A case of 22q11.2 deletion syndrome with right microphthalmia and left corneal staphyloma

Abstract Background: A microdeletion in the chromosome 22q11.2 (DiGeorge or velocardiofacial syndrome) is the most common human deletion syndrome. Patients with 22q11.2 deletion may have a wide range of ocular findings but severe ocular involvement is uncommon. Here, we describe a 2-year-old boy who had growth retardation, developmental delay, right renal agenesis, ventricular septal defect and severe bilateral ocular anomalies.

MATERIALS AND METHODS

The systemic and ocular findings and cranial magnetic resonance imaging study results were reviewed. Fluorescence in situ hybridization analysis was performed on his peripheral blood.

RESULTS

The patient presented with the oculodigital sign. On examination, he had severe right microphthalmia with no light perception and his left eye could not fix and follow. The left eye had anterior segment dysgenesis, mild sclerocornea, corneal staphyloma and congenital aphakia. Systemic findings included growth deficiency, microcephaly, micrognathia, ventricular septal defect, atrial septal defect and right renal agenesis. Fluorescence in situ hybridization analysis of this patient was significant for a heterozygous deletion covering DiGeorge critical region 2 and spanning a 250 kb region in the 22q11.2 locus.

CONCLUSION

The 22q11.2 deletion syndrome may be associated with severe bilateral ocular malformations including microphthalmia, sclerocornea, corneal staphyloma, anterior segment dysgenesis and congenital aphakia. Corneal staphyloma might have resulted from the oculodigital phenomenon or increased intraocular pressure.

Chromosome 22q11.2 deletion syndrome in African-American patients: a diagnostic challenge

Chromosome 22q11.2 deletion syndrome (22q11DS) is associated with numerous and variable clinical manifestations including conotruncal heart abnormalities, palatal anomalies, hypoparathyroidism, immune deficiency, and cognitive deficits. The clinical suspicion of this syndrome is often heightened by the presence of characteristic facial features. A previous report highlighted the under-diagnosis of this condition in African Americans, thought to be related to a paucity of typical facial features. We ascertained the largest cohort (n = 50) of African-American individuals with 22q11DS reported thus far, across five genetics centers in the United States and report on their facial and other phenotypic features. About 3/4 of our cohort has at least one dysmorphic facial feature. Auricular abnormalities, especially small ears, are the most common dysmorphic facial feature followed by nasal and ocular abnormalities. Skeletal findings are seen in about 2/3 of our cohort, higher than the typical frequency reported in 22q11DS. Cardiac anomalies, developmental delay, and palatal abnormalities are seen at a lower frequency in our cohort. Thus, it is evident that the features traditionally associated with 22q11DS are difficult to recognize in African-American individuals with this syndrome, due to both altered frequencies of major anomalies and a non-classic facial appearance. Therefore, a high index of suspicion is needed to recognize 22q11DS in African-American individuals.

Chromosome abnormalities and the genetics of congenital corneal opacification

Congenital corneal opacification (CCO) encompasses a broad spectrum of disorders that have different etiologies, including genetic and environmental. Terminology used in clinical phenotyping is commonly not specific enough to describe separate entities, for example both the terms Peters anomaly and sclerocornea have been ascribed to a clinical picture of total CCO, without investigating the presence or absence of iridocorneal adhesions. This is not only confusing but also unhelpful in determining valid genotype-phenotype correlations, and thereby revealing clues for pathogenesis. We undertook a systematic review of the literature focusing on CCO as part of anterior segment developmental anomalies (ASDA), and analyzed its association specifically with chromosomal abnormalities. Genes previously identified as being associated with CCO are also summarized. All reports were critically appraised to classify phenotypes according to described features, rather than the given diagnosis. Some interesting associations were found, and are discussed.

Unmasking of a Recessive SCARF2 Mutation by a 22q11.12 de novo Deletion in a Patient with Van den Ende-Gupta Syndrome

Van den Ende-Gupta syndrome (VDEGS) is a congenital condition characterized by craniofacial and skeletal manifestations, specifically blepharophimosis, malar and maxillary hypoplasia, distinctive nose, arachnocamptodactyly, and long slender bones of the hands and feet. To date, only 24 patients have been described. It is generally thought that the syndrome is transmitted by an autosomal recessive mode of inheritance, although evidence for genetic heterogeneity has recently been presented. We report on a girl followed from birth up to 3 years of life with a set of peculiar minor anomalies, arachnocamptodactyly of hands and feet, characteristic of VDEGS in association with a 22q11.12 deletion. Recently, the VDEGS gene was mapped to the DiGeorge syndrome region on 22q11.2, and homozygous mutations in the SCARF2 gene were identified. We now report the first patient with VDEGS due to compound heterozygosity for the common 22q11.2 microdeletion and a hemizygous SCARF2 splice site mutation.

Unilateral sclerocornea and tracheal stenosis: unusual findings in a patient with Goldenhar anomaly

The Goldenhar anomaly (GA) is a heterogeneous field defect of uncertain cause and wide variability of expression, characterized by facial phenotypes, usually asymmetric and unilateral, accompanied by various combinations and gradations of cardiac, skeletal, renal, and central nervous system defects. We report the pathologic findings in a 5-month-old boy with GA, tracheal stenosis, and left unilateral sclerocornea. To the best of our knowledge this is the first description of sclerocornea in a patient with GA.

Homozygous FOXE3 mutations cause non-syndromic, bilateral, total sclerocornea, aphakia, microphthalmia and optic disc coloboma

PURPOSE

To investigate the genetic basis of recessively-inherited congenital, non syndromic, bilateral, total sclerocornea in two consanguineous pedigrees, one from the Punjab province of Pakistan and the other from the Tlaxcala province of Mexico.

METHODS

Ophthalmic examinations were conducted on each family member to confirm their diagnosis and magnetic resonance imaging (MRI) or ultrasonography of the eyes was performed on some family members. Genomic DNA was analyzed by homozygosity mapping using the Affymetrix 6.0 SNP array and linkage was confirmed with polymorphic microsatellite markers. Candidate genes were sequenced.

RESULTS

A diagnosis of autosomal recessive sclerocornea was established for 7 members of the Pakistani and 8 members of the Mexican pedigrees. In the Pakistani family we established linkage to a region on chromosome 1p that contained Forkhead Box E3 (FOXE3), a strong candidate gene since FOXE3 mutations had previously been associated with various anterior segment abnormalities. Sequencing FOXE3 identified the previously reported nonsense mutation, c.720C>A, p.C240X, in the Pakistani pedigree and a novel missense mutation which disrupts an evolutionarily conserved residue in the forkhead domain, c.292T>C, p.Y98H, in the Mexican pedigree. Individuals with heterozygous mutations had no ocular abnormalities. MRI or ultrasonography confirmed that the patients with sclerocornea were also aphakic, had microphthalmia and some had optic disc coloboma.

CONCLUSIONS

This is the fourth report detailing homozygous FOXE3 mutations causing anterior segment abnormalities in human patients. Previous papers have emphasized aphakia and microphthalmia as the primary phenotype, but we find that the initial diagnosis - and perhaps the only one possible in a rural setting - is one of non-syndromic, bilateral, total sclerocornea. Dominantly inherited anterior segment defects have also been noted in association with heterozygous FOXE3 mutations. However the absence of any abnormalities in the FOXE3 heterozygotes described suggests that genetic background and environmental factors plays a role in the penetrance of the mutant allele.