Electroretinograms of eyes with Stickler syndrome

Severe foveal hypoplasia and macular degeneration in Stickler syndrome caused by missense mutation in COL2A1 gene

BACKGROUND

The aim is to determine the retinal changes in patients with Stickler syndrome caused by a p.R565C missense mutation of the COL2A1 gene.

METHODS

We reviewed the clinical records of 10 eyes of six patients from two families with the Stickler syndrome. The members of both families were heterozygous for the p.R565C mutation. The clinical features including the visual acuity, fundus appearances, fundus autofluorescence (FAF), optical coherence tomographic (OCT) images, and electroretinograms were examined.

RESULTS

Myopia of -12 diopters (D) to -24 D with an average of -16.8 D was observed in 9 eyes of the 5 patients. The FAF images showed different degrees of hyper and hypoautofluorescent patterns in the macula in all but the two youngest patients (7 of 9 eyes, 78%). The OCT images showed the absence of a foveal pit and destruction of the outer retinal layers in the macular area in all patients. The ellipsoid zone (EZ) in the macular region was disrupted in eight eyes (80%) of which seven were fovea sparing.

CONCLUSION

Two families with Stickler syndrome with the p.R565C mutation showed more severe foveal hypoplasia, macular degeneration, and extensive retinal degeneration. A correlation of the OCT and FAF images with the genotype is helpful in determining the prognosis of Stickler syndrome.

Retinal Features of Family Members With Familial Exudative Vitreoretinopathy Caused By Mutations in KIF11 Gene

Purpose

To determine the clinical characteristics of patients and family members with familial exudative vitreoretinopathy (FEVR) caused by mutations in the KIF11 gene.

Methods

Twenty-one patients from 10 FEVR families with mutations in the KIF11 gene were studied. The retinal and systemic features were examined. The genetic analyses performed included Sanger sequencing of the KIF11 gene, whole exome sequencing, as well as array comparative genomic hybridization (CGH) analysis and multiple ligation probe assay (MLPA).

Results

Sequence analysis revealed seven different KIF11 mutations. Array CGH with MLPA revealed two different exon deletions. All probands had advanced FEVR with retinal detachments (RDs) and microcephaly with or without developmental disabilities. Patients with bilateral RDs were more frequently associated with developmental disabilities (P = 0.023). Multimodal imaging of the family members revealed that six of nine patients without RDs (66%) had varying degrees of chorioretinopathy. The retinal folds in FEVR patients were associated with severe retinal avascularization. However, funduscopic changes in the peripheral retina were unremarkable in family members without RDs. A score representing the peripheral vascular anomalies determined from the fluorescein angiograms was lower than that of control eyes of patients with mutations of the Wnt signaling genes (P = 0.0029).

Conclusions

The probands with KIF11 mutations were associated with severe ocular and systemic pathologies, whereas affected family members showed highly variable clinical manifestations. Peripheral vascular anomalies can often be unremarkable in eyes without RDs.

Translational Relevance

These findings highlight more diverse mechanisms that underlie the pathological changes in patients with FEVR.

Transient electroretinographic abnormalities that mimic those of KCNV2 retinopathy: a case report

Purpose

The purpose of this report was to describe the case of a 68-year-old male patient with stage IV colon cancer who exhibited electroretinographic abnormalities that are similar to those of KCNV2 retinopathy.

Methods

The patient presenting with photophobia, reduced visual acuity, and poor general conditions, the onset of which occurred ten days before presentation, was examined using fundoscopy, full-field electroretinography, blood tests, and abdominal computed tomography.

Results

The patient’s decimal best-corrected visual acuity (BCVA) was 0.4 in each eye. Fundoscopy showed bull's eye-like maculopathy in both eyes. Electroretinographic findings were similar to the characteristic findings of KCNV2 retinopathy: Rod electroretinogram showed delayed and preserved b-wave amplitudes; bright-flash electroretinogram showed double troughs of a-waves; b/a ratios shown by bright-flash electroretinogram were higher than those shown by standard-flash electroretinogram; and both cone and 30-Hz flicker electroretinograms showed extinguished responses. His serum potassium level increased to 6.2 mmol/L (normal range 3.6–4.8 mmol/L) owing to hydronephrosis resulting from disseminated carcinoma. After performing an emergency surgery to treat this condition, the serum potassium level immediately decreased to a normal range. Eleven days after presentation, rod and standard/bright-flash electroretinography showed improvement in the implicit time of the rod b-waves and the a-waves. Unexpectedly, the responses recorded by cone and 30-Hz flicker electroretinography became normal. The symptoms and maculopathy disappeared, and his BCVA improved to 1.2.

Conclusions

The abnormal electroretinographic findings might be associated with the transient increase in serum potassium level.

ULTRA-WIDE FIELD FUNDUS AUTOFLUORESCENCE IMAGING OF EYES WITH STICKLER SYNDROME

PURPOSE

To determine the characteristics of fundus autofluorescence (FAF) images and visual functions in eyes with Stickler syndrome using ultra-widefield FAF images.

METHODS

Forty-six eyes of 26 patients with mutations in the COL2A1 gene underwent ultra-widefield FAF imaging. The eyes were categorized into three types; no signs of abnormal AF, predominantly hyperfluorescent AF (hyper-AF), and predominantly hypofluorescent AF (hypo-AF). Goldmann perimetry was performed on 34 eyes, and line-scan images of the abnormal AF lesions were obtained by swept-source optical coherence tomography in 4 eyes.

RESULTS

Abnormal AF lesions were found in 37 eyes of 21 (80.7%) of the 26 patients. Hyper-AF was found in 15 eyes and hypo-AF was found in 22 eyes. The FAF changes corresponded with the funduscopically observed radial paravascular retinal degeneration. The average age at the examination was significantly younger in patients who had eyes with hyper-AF or no abnormal AF than in those with hypo-AF (12.8 vs. 28.4 years; P = 0.009). Abnormal AF-associated visual field defects were found in 5/10 (50%) eyes with hyper-AF and 17/18 (94%) eyes with hypo-AF. Hyper-AF changes tended to appear before retinal changes were detectable by fluorescein angiography. An absence of the ellipsoid zone and the outer nuclear layer and a thinning of the overall retinal thickness were found corresponding to the hypo-AF lesions in the swept source optical coherence tomography images.

CONCLUSION

Abnormal FAF is characteristic of eyes with Stickler syndrome. Age-related alterations of the FAF was associated with visual field defects and disruption of the photoreceptors and retinal pigment epithelial cells.

Autosomal recessive Stickler syndrome associated with homozygous mutations in the COL9A2 gene

Background: Stickler syndrome is a hereditary disorder of collagen tissues causing ocular, auditory, orofacial, and joint manifestations. Ocular findings typically include vitreous degeneration, high myopia, retinal detachment, and cataract. Many subjects demonstrate sensorineural or conductive hearing loss. The inheritance is autosomal dominant with mutations in COL2A1, COL11A1, or COL11A2 or autosomal recessive due to mutations in COL9A1, COL9A2, or COL9A3. We describe a family with Stickler syndrome caused by homozygous loss-of-function mutations in COL9A2.Methods: Two brothers from a consanguineous family were examined with genetic testing, visual acuity, Goldmann perimetry, full-field and multifocal electroretinography (ffERG, mERG), optical coherence tomography (OCT), fundus autofluorescence (FAF), fundus photography, and pure-tone audiograms.Results: Both subjects were homozygous for the mutation c.1332del in COL9A2. Their parents were heterozygous for the same mutation. The boys demonstrated reduced visual acuity, vitreous changes and myopia. The proband was operated for retinal detachment and cataract in one eye. FfERG revealed reduced function of both rods and cones and mERG showed reduced macular function. No morphological macular changes were found by OCT or FAF. Both brothers have severe sensorineural hearing loss with down-sloping audiograms but only subtle midface hypoplasia and no, or mild joint problems.Conclusion: Only a few families with Stickler syndrome caused by COL9A2 mutations have been reported. We confirm previous descriptions with a severe ocular and auditory phenotype but mild orofacial and joint manifestations. Moreover, we demonstrate reduced macular and overall retinal function explaining the reduced visual acuity in patients with Stickler syndrome also without retinal complications.