Hereditary optic pit and iris coloboma in three generations of a single family

Ocular coloboma-a comprehensive review for the clinician

Typical ocular coloboma is caused by defective closure of the embryonal fissure. The occurrence of coloboma can be sporadic, hereditary (known or unknown gene defects) or associated with chromosomal abnormalities. Ocular colobomata are more often associated with systemic abnormalities when caused by chromosomal abnormalities. The ocular manifestations vary widely. At one extreme, the eye is hardly recognisable and non-functional—having been compressed by an orbital cyst, while at the other, one finds minimalistic involvement that hardly affects the structure and function of the eye. In the fundus, the variability involves the size of the coloboma (anteroposterior and transverse extent) and the involvement of the optic disc and fovea. The visual acuity is affected when coloboma involves disc and fovea, or is complicated by occurrence of retinal detachment, choroidal neovascular membrane, cataract, amblyopia due to uncorrected refractive errors, etc. While the basic birth anomaly cannot be corrected, most of the complications listed above are correctable to a great extent. Current day surgical management of coloboma-related retinal detachments has evolved to yield consistently good results. Cataract surgery in these eyes can pose a challenge due to a combination of microphthalmos and relatively hard lenses, resulting in increased risk of intra-operative complications. Prophylactic laser retinopexy to the border of choroidal coloboma appears to be an attractive option for reducing risk of coloboma-related retinal detachment. However, a majority of the eyes have the optic disc within the choroidal coloboma, thus making it difficult to safely administer a complete treatment.

Progressive optic nerve changes in cavitary optic disc anomaly: integration of copy number alteration and cis-expression quantitative trait loci to assess disease etiology

Background

We performed clinical and genetic characterization of a family with cavitary optic disc anomaly (CODA), an autosomal dominant condition that causes vision loss due to adult-onset maculopathy in the majority of cases. CODA is characterized by a variably excavated optic nerve appearance such as morning glory, optic pit, atypical coloboma, and severe optic nerve cupping.

Methods

Four affected and fourteen unaffected family members of a multi-generation pedigree were phenotyped by visual acuity, intraocular pressure, dilated fundus examination, fundus photography, and optical coherence tomography. Genetic analysis was performed by breakpoint polymerase chain reaction (PCR), long range PCR, and direct Sanger sequencing. The functional relevance of the copy number alteration region was assessed by in silico analysis.

Results

We found progressive optic nerve cupping in three affected members of a family with CODA. In one individual, an optic pit developed over time from a normal optic nerve. By two independent methods, we detected a previously described intergenic triplication that segregated with disease in all adults of the family. The copy number alteration was also detected in five children with normal optic nerves. eQTL analysis demonstrated that this CNA region regulates expression of up to 4 genes in cis.

Conclusions

Morning glory, optic pit and atypical coloboma are currently considered congenital anomalies of the optic nerve, but our data indicate that in CODA, the excavated optic nerve appearance may develop after birth and into adulthood. In silico analysis of the CNA, may explain why vairable expressivity is observed in CODA.

Electronic supplementary material

The online version of this article (10.1186/s12881-019-0800-4) contains supplementary material, which is available to authorized users.

Intrafamilial heterogeneity of congenital optic disc pit maculopathy

BACKGROUND

Optic disc pit is a very rare clinical entity. The main complication of this condition is the maculopathy. Report of cases: A 40-year-old Caucasian man and his 6-year-old daughter underwent a complete ophthalmological examination. In both cases ophthalmoscopy examination showed a bilateral white-yellow oval depression in the optic disc. Optical coherence tomography showed maculopathy with different degrees of severity in the two cases. Microperimetry and multifocal-electroretinography showed different degrees of retinal dysfunction in both cases. Molecular genetic analysis was performed and the possible pathogenic role of the MIR204 gene was excluded.

DISCUSSION

The findings of our familial cases support the hypothesis that optic disc pit associated with maculopathy could be a genetic disease with an autosomal dominant inheritance pattern. Optical coherence tomography is the most helpful diagnostic tool to assess maculopathy associated with optic disc pit. Microperimetry and multifocal-electroretinography are useful for the diagnosis of macular dysfunction in the early stages, and for the prognosis and follow-up of optic disc pit-maculopathy which is the main cause of visual impairment in these patients. Furthermore, in consideration of the variable expressivity and disease severity reported in our cases, genetic anticipation may be hypothesized.

PERIPHERAL AVASCULAR RETINA WITH DISK ANOMALY AND HIGH MYOPIA: A Novel Association in a Hereditary Isolated Ocular Disorder

PURPOSE

To describe a family pedigree with a previously undescribed association of autosomal dominantly inherited ocular abnormalities.

METHODS

Case series study performed on 15 family members. Examination included history taking, visual acuity, intraocular pressure, slit-lamp, gonioscopy, indirect ophthalmoscopy (10 members), fluorescein angiography (5 members), general examination and renal ultrasound (4 members), and hemoglobin electrophoresis for the proband and another member.

RESULTS

Family pedigree revealed autosomal-dominant inheritance. Visual acuity ranged from 6/36 to no light perception. Examination revealed rubeosis in 7 eyes and atrophia bulbi in 11 eyes. Indirect ophthalmoscopy for 11 eyes revealed evidence of an ocular triad of peripheral avascular retina, disk anomaly (cavitary optic disk anomaly or disk dysplasia), and tessellated fundus of high myopia. The authors also observed new vessels elsewhere with or without extensive subretinal exudations in 6 eyes. All patients with any residual vision (up to perception of light) had nystagmus. Four affected members underwent general examination, renal ultrasound, and serum creatinine level (to exclude papillorenal syndrome), and all were normal. Hemoglobin electrophoresis (to exclude sickle cell retinopathy) revealed within normal values.

CONCLUSION

To the authors' knowledge, the aforementioned ocular triad has not been previously described, in association, with an autosomal-dominant pattern of inheritance.

Biochemical Basis for Dominant Inheritance, Variable Penetrance, and Maternal Effects in RBP4 Congenital Eye Disease

Gestational vitamin A (retinol) deficiency poses a risk for ocular birth defects and blindness. We identified missense mutations in RBP4, encoding serum retinol binding protein, in three families with eye malformations of differing severity, including bilateral anophthalmia. The mutant phenotypes exhibit dominant inheritance, but incomplete penetrance. Maternal transmission significantly increases the probability of phenotypic expression. RBP normally delivers retinol from hepatic stores to peripheral tissues, including the placenta and fetal eye. The disease mutations greatly reduce retinol binding to RBP, yet paradoxically increase the affinity of RBP for its cell surface receptor, STRA6. By occupying STRA6 nonproductively, the dominant-negative proteins disrupt vitamin A delivery from wild-type proteins within the fetus, but also, in the case of maternal transmission, at the placenta. These findings establish a previously uncharacterized mode of maternal inheritance, distinct from imprinting and oocyte-derived mRNA, and define a group of hereditary disorders plausibly modulated by dietary vitamin A.

A clinical and optical coherence tomography study of choroidal colobomas

PURPOSE OF REVIEW

This paper reviews current understanding of coloboma of the choroid, as evaluated clinically and using optical coherence tomography.

RECENT FINDINGS

Studies of the margin of coloboma of the choroid with optical coherence tomography revealed several interesting features, including variability in transition from normal retina to intercalary membrane (gradual or abrupt), presence of subclinical retinal detachments, focal communications between the subretinal space and subintercalary membrane space in eyes with extra-colobomatous retinal detachments, and inward humping of the eye wall in some cases. Pathological studies have stressed the importance of the intercalary membrane and the margin of coloboma as barriers for occurrence of retinal detachments. Vitrectomy and silicone oil tamponade could correct these retinal detachments in a majority of cases.

SUMMARY

Optical coherence tomography can provide insight into pathology at the margin of the coloboma. Coupled with knowledge from histopathological studies, this information can guide the management of retinal detachments secondary to coloboma of the choroid with a high degree of success.