CCDD Phenotype Associated with a Small Chromosome 2 Deletion

Abstract

Purpose: Some individuals are born with congenital limitation of ocular motility, often associated with ptosis and retraction of the globe. Many of these disorders are now known as the congenital cranial dysinnervation disorders (CCDDs). While several genes have been associated with CCDD phenotypes, there are still patients for whom the genetic basis has not been identified. Methods: Clinical evaluation and neuroimaging, sequencing of candidate genes, and array comparative genomic hybridization (array CGH). Results: The patient was a four-year-old girl with mild dysmorphism; bilateral mild ptosis; substantial limitation of abduction OS with milder limitations of abduction OD, adduction OS, and vertical gaze OS; and retraction OS?>?OD on attempted adduction. No mutations were detected in the HOXA1, KIF21A, SALL4, TUBB3, and CHN1 genes. Array CGH revealed a 8 Kb de novo deletion on chromosome 2 (2q24.3) that encompassed a portion of only one gene, the Xin Actin-binding Repeat containing 2 (Gene Symbol XIRP2; NM_001079810). This gene encodes a protein that is involved in muscle development and protecting actin filaments from depolymerization. It interacts functionally with 10 other proteins playing a similar role in muscle development. Conclusions: This patient’s chromosomal abnormality affected only one gene that currently seems involved only in muscle development. All other genes currently associated with the CCDDs affect neurologic development. Genetic information from this patient implies that genes involved in development and maintenance of extraocular muscles can cause congenital ocular motility disorders as well.     

Great clinical variability of Nance Horan syndrome due to deleterious NHS mutations in two unrelated Spanish families

ABSTRACT

Background: Nance-Horan syndrome (NHS) is an X-linked rare congenital disorder caused by mutations in the NHS gene. Clinical manifestations include congenital cataracts, facial and dental dysmorphism and, in some cases, intellectual disability. The aim of the present work was to identify the genetic cause of this disease in two unrelated Spanish NHS families and to determine the relative involvement of this gene in the pathogenesis.

Materials and methods: Four members of a two-generation family, three males and one female (Family 1), and seven members of a three-generation family, two males and five females (Family 2) were recruited and their index cases were screened for mutations in the NHS gene and 26 genes related with ocular congenital anomalies by NGS (Next Generation Sequencing).

Results: Two pathogenic variants were found in the NHS gene: a nonsense mutation (p.Arg373X) and a frameshift mutation (p.His669ProfsX5). These mutations were found in the two unrelated NHS families with different clinical manifestations.

Conclusions: In the present study, we identified two truncation mutations (one of them novel) in the NHS gene, associated with NHS. Given the wide clinical variability of this syndrome, NHS may be difficult to detect in individuals with subtle clinical manifestations or when congenital cataracts are the primary clinical manifestation which makes us suspect that it can be underdiagnosed. Combination of genetic studies and clinical examinations are essential for the clinical diagnosis optimization.     

Prevalence of Congenital Ocular Anomalies among Children with Genetic Disorders: An Egyptian Study

Purpose: To assess the pattern and frequency of occurrence of ocular anomalies among other genetic disorders in Egypt. Methods: This is a cross-sectional study of 2500 cases presenting with genetic disorders. Cases were recruited from the clinical genetics department of the National Research Centre (NRC) over a four-year period between January 2011 and December 2014. Ophthalmological examination of the cases was performed in the pediatric ophthalmology department of Cairo University Hospitals. Results: Out of 2500 cases with congenital disorders, 2.4% suffered one or more ocular anomalies with a male to female ratio of 1.7:1. Consanguinity was reported in 76.7% and family history was positive in 35% of ocular cases. The most common ocular anomalies were congenital cataract, retinal dystrophies, glaucoma, and retinoblastoma in order of frequency. Chromosomal aberrations were detected in two retinoblastoma cases and in one case of charge association with cataract and iris coloboma. A truncating mutation in exon 8 of OCRL1 was reported in a case of Lowe syndrome with cataract. A total of 51.7% of ocular cases were non-isolated (associated with other genetic disorders). Conclusion: In Egypt, ocular genetic disorders are not uncommon among other genetic disorders. Consanguinity is high, suggesting high incidence of autosomal recessive inheritance of genetic disorders with an ocular component. Proper systemic assessment of all cases with ocular anomalies is a necessity due to the high percentage of non-isolated ocular anomalies. Genetic counseling of parents would help in reducing recurrence rates through prenatal diagnosis whenever possible.     

Evidence for genetic heterogeneity in families with congenital motor nystagmus (CN)

Background: Wolfram syndrome is characterized by optic atrophy, insulin dependent diabetes mellitus, diabetes insipidus and deafness. There are several other associated conditions reported in the literature, but congenital or early childhood cataracts are not among them.

Materials and methods: Observational case series with confirmatory genetic analysis.

Results: A pair of siblings, followed over 17 years, who manifest congenital or early childhood cataracts, diabetes insipidus, diabetes mellitus, optic atrophy, and deafness. They are both compound heterozygotes for mutations (V415 deletion and A684V substitution) in the WFS1 gene. Their father has congenital sensorineural hearing loss and developed optic atrophy. He is heterozygous for A684V in WFS1.

Conclusions: Wolfram syndrome should be in the differential diagnosis of genetic syndromes associated with congenital and early childhood cataracts. Here, we report on a mother who is a phenotypically normal carrier of an autosomal recessive Wolfram syndrome gene, and a father who has some of the findings of the syndrome and carries a single mutation that appears to be responsible for his hearing loss and optic atrophy. Their 2 children are compound heterozygotes and manifest the full Wolfram syndrome, in addition to cataracts.     

Möbius syndrome with cardiac rhabdomyomas

Background: Möbius syndrome is a rare congenital condition which presents not merely with 6th and 7th nerve palsies, but involves gaze paresis associated with craniofacial, limb, and other abnormalities. Heterogeneity is well known in patients with Möbius syndrome and rather than being of familial inheritance based on rare cases, it is much more recognized as a sporadic syndrome. We report an infant with features of congenital Möbius syndrome associated with cardiac rhabdomyomas in the absence of tuberous sclerosis.

Materials and methods: Observational case report of an infant seen at a tertiary academic center with genetic testing, ophthalmic, neurological, and cardiac clinical examination and imaging.

Results: A newborn baby boy at birth was seen with multiple congenital craniofacial malformations, and respiratory distress. He was noted to have micrognathia, retrognathia, wide nasal bridge, low set ears, high arched palate, nonreducing bilateral talipes equinovarus and bilateral large angle esotropia with ?4 abduction deficit and facial palsy, findings suggestive of Möbius Syndrome. MRI of the brain was unremarkable except for syringomyelia in the cervical spine. Echocardiography showed two cardiac rhabdomyomas in the right ventricle and ulltrasound of the abdomen showed mild right hydroneprosis. Cytogenetics revealed segmental loss at 21q21.2. Testing for tuberous sclerosis was negative for deletion or duplications of genes TSC1 and TSC2.

Conclusion: This case highlights the rare co-occurrence of cardiac rhabdomyomas with Möbius syndrome and new segmental loss at 21q21.2 on genetic testing. Findings could indicate not a “suggestion of Möbius”, but rather the syndrome itself in association with cardiac defects.     

Genetic screening of Russian Usher syndrome patients toward selection for gene therapy

ABSTRACT

Background: Usher syndrome (USH) is heterogeneous in nature and requires genetic test for diagnosis and management. Mutations in USH associated genes are reported in some populations except Russians. Here, we first time represented the mutation spectrum of a Russian USH cohort.

Methods: Twenty-eight patients with USH were selected from 3214 patients from Deaf-Blind Support Foundation “Con-nection” during 2014–2016 following the observational study NCT03319524. Complete ophthalmologic, ENT, and vestibular medical tests were done for clinical characterization. NGS, MLPA, and Sanger sequencing were considered for genetic analysis.

Results: Around 53.57% and 39.28% patients had USH1 and USH2, respectively; 17.85% cases (n = 5/28) had no known mutation. Eleven (73.33%) subjects showed variations in USH1 associated genes MYO7A (72.72%), CDH23 (9.09%), PCDH15 (9.09%), and USH1C (9.09%). Eleven mutations are detected in MYO7A where 54.54% are novel. MYO7A: p.Q18* was most frequent (27.27%) mutation and is associated with early manifestation and most severe clinical picture. Two novel mutations (p.E1301* and c.158-?_318+?del) are detected in PCDH15 gene. Around 90.90% patients suspected to be USH2 are confirmed by genetic testing. Eleven mutations detected in the USH2A gene, where 27.27% were novel. Most common USH2A mutation is p.W3955* (50%) followed by p.E767fs, p.R1653*, and c.8682-9A> G (20% each).

Conclusion: The Russian USH cohort shows both novel and known USH mutations. Clinically the prevalence of USH2 is low (39.28%) and the frequency of MYO7A mutations responsible for USH1B is very high (63.63%, N = 7/11) compared to other cohorts. These seven patients carrying MYO7A mutations are preliminarily eligible for the UshStat® gene therapy.     

Congenital cranial dysinnervation disorders

The European Neuromuscular Centre (ENMC) derived the term Congenital Cranial Dysinnervation Disorders in 2002 at an international workshop for a group of congenital neuromuscular diseases. CCDDs are congenital, non-progressive ophthalmoplegia with restriction of globe movement in one or more fields of gaze. This group of sporadic and familial strabismus syndromes was initially referred to as the 'congenital fibrosis syndromes' because it was assumed that the primary pathologic process starts in the muscles of eye motility. Over the last few decades, evidence has accumulated to support that the primary pathologic process of these disorders is neuropathic rather than myopathic. This is believed that for normal development of extra ocular muscles and for preservation of muscle fiber anatomy, normal intra-uterine development of the innervation to these muscles is essential. Congenital dysinnervation to these EOMs can lead to abnormal muscle structure depending upon the stage and the extent of such innervational defects. Over last few years new genes responsible for CCDD have been identified, permitting a better understanding of associated phenotypes, which can further lead to better classification of these disorders. Introduction of high-resolution MRI has led to detailed study of cranial nerves courses and muscles supplied by them. Thus, due to better understanding of pathophysiology and genetics of CCDDs, various treatment modalities can be developed to ensure good ocular alignment and better quality of life for patients suffering from the same.     

Analysis of the SALL4 Gene in Patients with Duane Retraction Syndrome in a South Indian Population

Duane retraction syndrome (DRS) is a congenital eye movement disorder characterized most typically by partial or complete failure of abduction and narrowing of palpebral fissure with globe retraction on adduction. Recently mutations of the SALL4 gene on chromosome 20 have been linked to DRS associated with radial forearm malformations (Okihiro syndrome). In this prospective, non-interventional study we screened for SALL4 mutations in 72 patients clinically diagnosed as having isolated DRS or DRS associated syndromes. All four exonic and the neighboring intronic regions of SALL4 gene were amplified by sixteen sets of primers using polymerase chain reaction and were subjected to bi-directional sequencing and BLAST analysis. No genetic variations were detected in the coding region and in the neighboring intronic regions of the SALL4 gene suggesting an alternative mechanism in the pathogenesis of these disorders in the South Indian population.     

A New Case of Keratoconus Associated with Williams-Beuren Syndrome

ABSTRACT

Background: Williams-Beuren syndrome is a multisystemic genetic disorder caused by a contiguous gene deletion at 7q11.23. Keratoconus is a complex disease and it is suspected to have a genetic origin, although the specific gene responsible for keratoconus has not been identified. Although there are several ocular features in Williams-Beuren syndrome, keratoconus is not regularly described as part of this syndrome.

Purpose: To report a new patient with keratoconus and Williams-Beuren syndrome.

Discussion: This is the third case of an association between Williams-Beuren syndrome and keratoconus. The authors believe that the Williams-Beuren syndrome chromosome region can be a possible target for further investigation as the genetic basis of keratoconus.     

Preimplantation genetic diagnosis as a strategy to prevent having a child born with an heritable eye disease

Background: In developed countries, genetically inherited eye diseases are responsible for a high percentage of childhood visual impairment. We aim to report our experience using preimplantation genetic diagnostics (PGD) in order to avoid transmitting a genetic form of eye disease associated with childhood visual impairment and ocular cancer.

Material and Methods: Retrospective case series of women who underwent in vitro fertilization (IVF) and PGD due to a familial history of inherited eye disease and/or ocular cancer, in order to avoid having a child affected with the known familial disease. Each family underwent genetic testing in order to identify the underlying disease-causing mutation. IVF and PGD treatment were performed; unaffected embryos were implanted in their respective mothers.

Results: Thirty-five unrelated mothers underwent PGD, and the following hereditary conditions were identified in their families: albinism (10 families); retinitis pigmentosa (7 families); retinoblastoma (4 families); blue cone monochromatism, achromatopsia, and aniridia (2 families each); and Hermansky-Pudlak syndrome, Leber congenital amaurosis, Norrie disease, papillorenal syndrome, primary congenital cataract, congenital glaucoma, Usher syndrome type 1F, and microphthalmia with coloboma (1 family each). Following a total of 88 PGD cycles, 18 healthy (i.e., unaffected) children were born.

Conclusions: Our findings underscore the importance an ophthalmologist plays in informing patients regarding the options now available for using prenatal and preimplantation genetic diagnosis to avoid having a child with a potentially devastating genetic form of eye disease or ocular cancer. This strategy is highly relevant, particularly given the limited options currently available for treating these conditions.     

Retinal detachment and infantile-onset glaucoma in Stickler syndrome associated with known and novel COL2A1 mutations

Background: Few reports on surgical outcomes after retinal detachment in Stickler syndrome exist. Also, infantile-onset glaucoma associated with Stickler syndrome has been rarely reported and no reports exist that examine outcomes after glaucoma surgery. This study describes the clinical and genetic associations and the long-term outcomes of retinal detachment repair or glaucoma surgery in patients with Stickler syndrome.

Materials and Methods: Retrospective, single-center, case series of patients with Stickler syndrome. Demographics, clinical features, genetic mutations, and long-term surgical outcomes of eyes that experienced retinal detachment or diagnosed with infantile-onset glaucoma were assessed.

Results: Fifteen patients were identified with a mean age of 13 years at presentation and followed for a mean of 6 years. Two-thirds were male. Genetic analysis was performed as part of routine examination in nine patients from eight families. All were identified as having variants in COL2A1, three of which were novel. Six eyes of six patients experienced retinal detachment. Fifty percent of eyes without prophylactic laser treatment experienced retinal detachment, whereas only 5% of eyes that underwent prophylactic therapy detached. Despite surgical intervention for retinal detachment, five eyes became phthisical. Five eyes of three patients were diagnosed with infantile-onset glaucoma. All five eyes required multiple glaucoma surgeries, and three eyes became phthisical.

Conclusions: This study illustrates the surgical challenges encountered in patients with Stickler syndrome. Additionally, infantile-onset glaucoma may be more prevalent than previously reported and presents a challenge in terms of management. A multidisciplinary approach is recommended to provide optimal care to these patients.     

Late diagnosis of Alstrom syndrome in a Yemenite-Jewish child

Background: We describe the ophthalmologic, clinical, and genetic findings in a patient of Yemenite-Jewish origin diagnosed with Alstrom syndrome due to a novel splice-site mutation 10 years after a clinical misdiagnosis of Leber congenital amaurosis.

Methods: Ophthalmological evaluations included visual acuity, cycloplegic refraction, slit-lamp, and optical coherent tomography. Genetic analyses included whole exome sequencing followed by bioinformatics analysis and segregation analysis. An in vitro splicing assay was used to evaluate the effect of the identified mutation on splicing. Taqman assay was used to determine the need for population screening for the identified mutation.

Results: Ophthalmologic findings at age 6 were impaired vision, nystagmus, and hyperopia. At age 16 years, the patient presented with obesity, hypothyroidism, and elevated transaminase levels in addition to reduced vision, wandering nystagmus, disc pallor, and degenerative retinal changes. Targeted genetic analysis of ALMS1 revealed a homozygous transversion, c.11544 + 3A>T, suggesting a novel splicing mutation, with elimination of the donor splice site and insertion of 73 nucleotides at the end of exon 16. These changes were validated by Sanger sequencing and co-segregation on family members.

Conclusions: Ophthalmologists should be alert to the differential diagnosis of inherited retinal degeneration in young patients who present with impaired vision, especially if systemic symptoms are mild and there is no known family history. In the present case, targeted genetic analysis of a child with a syndromic cone-rod dystrophy yielded a novel splicing mutation in ALMS1 causing Alstrom syndrome.     

Blau Syndrome-Associated Uveitis and the NOD2 Gene

Abstract

Blau syndrome (BS), a rare autosomal dominant autoinflammatory syndrome, is an example of a monogenic disease. It was first described as a classic triad of uveitis, arthritis, and exanthema, typically seen in patients less than four years of age. Since that time, the phenotype has been expanded to include fever, cranial neuropathies, cardiovascular abnormalities, and granulomas of the liver and kidney. The ocular inflammation is often a panuveitis that occurs later in the disease course and typically carries the greatest morbidity in BS. BS has been mapped to the chromosomal region 16q12-21, also known as the NOD2 gene (formerly CARD15/NOD2). The disease is secondary to a single amino acid mutation NOD2 that leads to peptidoglycan-independent activity of nuclear factor (NF)–κB. Clinical and genetic aspects of BS will be discussed, as well as recent advances in treatment protocols.     

Case report of four siblings in southeast Turkey with a novel RAB3GAP2 splice site mutation: Warburg micro syndrome or Martsolf syndrome?

Background: Warburg micro syndrome is a very rare autosomal recessive disorder characterized by a mutation in the RAB3GAP1, RAB3GAP2, RAB18, and TBC1D20 genes. Warburg Micro syndrome 2 and Martsolf syndrome are clinically overlapping conditions characterized by variable clinical signs counting postnatal growth retardation, cataract, intellectual deficiency, contractures, and central nervous system abnormalities due to RAB3GAP2 gene mutations. The RAB3GAP2 gene encodes a member of the Rab3 protein family, which is involved in regulated exocytosis of neurotransmitters and hormones.

Case presentation: We describe four siblings from healthy consanguineous Turkish parents with developmental delay, congenital cataract, and speech delay. In this study, we performed whole exom sequencing (WES) in a index patient. WES analyses in proposita showed a homozygous c.1998 + 1 G > A mutation in RAB3GAP2 gene. After the Sanger confirmation, the same mutation was detected in the other three siblings.

Conclusion: The four siblings had a novel splice site mutation in RAB3GAP2. This report compares the symptoms and features of the our patients with clinical summary of Warburg Micro syndrome 2 and Martsolf syndrome. Further reports will make possible knowing of the genetic and clinical backgrounds of this orphan diseases.

Abbreviation: MRI: Magnetic resonance imaging     

Double Jeopardy: Blepharophimosis Syndrome with Congenital Nasolacrimal Duct Obstruction in Twins

ABSTRACT

Purpose: Blepharophimosis-ptosis-epicanthus inversus syndrome (BPES) is an autosomal dominant disorder characterized by bilateral ptosis with poor levator function, epicanthus inversus and shortened horizontal palpebral fissures. Method: Eighteen -month -old twin sisters presented with history of watering from their left eyes since birth. Examination revealed features of BPES with left congenital nasolacrimal duct obstruction in both. Result: the twins underwent therapeutic probing, which was successful in one and failed in the other. the second child was subsequently managed by external dacryocystorhinostomy. Conclusion: To our knowledge, this is the first report of Blepharophimosis syndrome with congenital nasolacrimal duct obstruction occurring in twin sisters.     

Genetic analysis of patients with primary congenital glaucoma

Purpose

To determine the common gene mutation in patients with primary congenital glaucoma (PCG) in the Southeast region of Turkey via genetic analysis and to evaluate whether there were other gene mutations in these patients.

Methods

A total of 25 patients with PCG were included in this study. We performed sequence analysis including all exons of cytochrome p450 1B1 (CYP1B1), myocilin (MYOC), forkhead box C1 (FOXC1), and paired-like homeodomain 2 (PITX2) genes of the obtained samples. Further, we analyzed the results using the Nextgen analysis program.

Results

The CYP1B1 gene mutation was detected in 20 (80%) of 25 patients, and FOXC1 gene mutation was detected in one (4%) patient. The mutation site of nine (45%) of the 20 CYP1B1 genes was found in the second exon. The pathogenic variant (p.Gly61Glu) was observed in 12 (60%) patients (in the first and second exons); the mutation type of six (50%) of these patients was homozygous. The mutation site of one patient with FOXC1 gene mutation was found to be in the first exon; its pathogenic variant was p.Met400lle. The mutation type in this gene was observed to be heterozygous. Lastly, there were no mutations in the MYOC, FOXC1, and PITX2 genes in combination with the CYP1B1 gene mutation.

Conclusion

The most common cause of PCG in our region is the CYP1B1 gene mutation, and the most frequent pathogenic variant is c.182G?>?A (p.Gly61Glu). We also determined that the CYP1B1 gene mutation was alone and did not occur with other gene mutations (MYOC, FOXC1, and PITX2).

     

Genetic factors influencing the reduction of central corneal thickness in disorders affecting the eye

Background: The aim was to summarize and discuss the current knowledge about genetic factors influencing the reduction of central corneal thickness (CCT) in disorders affecting the eye, such as primary open-angle glaucoma (POAG), brittle cornea syndrome (BCS), keratoconus (KTCN), Ehlers–Danlos syndrome (EDS; types I, II, and VI), osteogenesis imperfecta (OI), and myopia.

Materials and methods: A review of the published literature by use of key databases such as PubMed was undertaken in accordance with PRISMA guidelines and experience based on own research findings was applied.

Results: The differences in CCT measurements among those affected with diverse disorders and healthy individuals were evaluated. Then we considered the influence of genetic factors on CCT reduction. Disorders were compared based on phenotypes and sequence variants found in patients.

Conclusions: Specific sequence variants in COL8A2, PRDM5 and ZNF469, COL5A1 and ZNF469, and COL5A1 and COL5A2 could probably contribute to a CCT reduction in POAG, BCS, KTCN, and EDS, respectively. Similar sequence variants and phenotypes were identified and assessed in more than one disease.     

New Corneal Findings in Chromosome 10 Deletion Syndrome: Report of Two Cases of Corneal Ectasia of Varying Severity

Abstract

Purpose: To describe corneal changes associated with chromosome 10 terminal deletion (chromosome 10, monosomy 10qter) syndrome. Methods: Report of two cases of bilateral corneal ectasia with literature review. Results: Corneal pathology has not previously been reported in the limited number of case reports on 10qter syndrome. However, Rodrigues et al.¹ have reported sclerocornea in 10q translocation. Conclusions: Ophthalmic manifestations of 10qter syndrome include strabismus, lid, and facial anomalies. We present two cases of corneal ectasia of varying severity. Possible etiologies include the following: secondary to genetic factors, acquired corneal exposure during sleep, or possible intrinsic immunocompromise exacerbating ocular surface infections. Corneal ectasia with specific histological changes is a feature of various genetic disorders (e.g., Down’s, Ehler’s Danlos, and Marfan’s syndromes). It is unknown whether genetics plays a role in the development of corneal changes in 10qter syndrome. Management of inflammation and visual rehabilitation in these patients poses a therapeutic challenge.     

A Review of the Clinical and Genetic Aspects of Aniridia

Abstract

Aniridia classically presents with a bilateral congenital absence or malformation of the irides, foveal hypoplasia, and nystagmus, and patients tend to develop visually significant pre-senile cataracts and keratopathy. Additionally, they are at high risk for developing glaucoma. Classic aniridia can be genetically defined as the presence of a PAX6 gene deletion or loss-of-function mutation that results in haploinsufficiency. Variants of aniridia, which include a condition previously referred to as autosomal dominant keratitis, are likely due to PAX6 mutations that lead to partial loss of PAX6 function. Aniridia-associated keratopathy (AAK) is a progressive and potentially debilitating problem affecting aniridic patients. The current treatments for AAK are to replace the limbal stem cells through keratolimbal allograft (KLAL) with or without subsequent keratoplasty for visual rehabilitation, or to implant a Boston type 1 keratoprosthesis. Future therapies for AAK may be aimed at the genetic modification of corneal limbal stem cells.