Inspired by a patient
Abstract
Purpose: To describe a case of microcephaly, unilateral retinal fold, and familial exudative vitreoretinopathy (FEVR)-like phenotype in the context of 2 TUBGCP6 variants. Methods: A case and its findings were analyzed. Results: A 4-month-old boy with no family history of eye disease presented by referral for management of presumed persistent fetal vasculature in the left eye. An external examination showed microcephaly. The patient grimaced to light in both eyes, and the anterior segments were unremarkable. On dilated fundus examination, diffuse chorioretinal atrophy was present bilaterally. In the left eye, a retinal fold emanated from the optic nerve head. There was early termination of retinal vasculature, especially in zone 3 in the left eye, resembling a FEVR-like phenotype. Panel-based genetic testing was performed and found 2 mutations in TUBGCP6. Conclusions: Microcephaly, chorioretinopathy, and retinal folds may be associated with TUBGCP6 mutations and masquerade as PFV.
Shurygina MF, Simonett JM, Parker MA, Mitchell A, Grigorian F, Lifton J, Nagiel A, Shpak AA, Dadali EL, Mishina IA, Weleber RG, Yang P, Pennesi ME. Genotype Phenotype Correlation and Variability in Microcephaly Associated With Chorioretinopathy or Familial Exudative Vitreoretinopathy. Invest Ophthalmol Vis Sci. 2020 Nov 2;61(13):2. doi: 10.1167/iovs.61.13.2. PMID: 33137195; PMCID: PMC7645200.
Abstract
Purpose: The purpose of this study was to analyze the natural history and phenotypic overlap of patients with microcephaly and a chorioretinopathy or familial exudative vitreoretinopathy (FEVR) ocular phenotype caused by mutations in KIF11, TUBGCP4, or TUBGCP6.
Methods: Patients diagnosed with congenital microcephaly and chorioretinopathy or FEVR were included. Molecular investigations consisted of targeted genetic sequencing. Data from medical records, ophthalmologic examination and imaging, electroretinography, and visual fields were analyzed for systemic and ophthalmic features and evidence of posterior segment disease progression.
Results: Twelve patients from 9 families were included and had a median of 8 years of follow-up. Nine patients had KIF11 variants, two had heterozygous TUBGCP6 variants, and one had heterozygous variants in TUBGCP4. All patients had reduced visual function and multiple individuals and families showed features of both chorioretinopathy and FEVR. Progression of posterior segment disease was highly variable, with some degree of increased atrophy of the macula or peripheral retina or increased vitreoretinal traction observed in 9 of 12 patients.
Conclusions: Microcephaly due to mutations in KIF11, TUBGCP4, or TUBGCP6 can be associated with retinal disease on a spectrum from chorioretinal atrophy to FEVR-like posterior segment changes. Visually significant disease progression can occur and patients should be monitored closely by a team experienced in ophthalmic genetics.
Hull S, Arno G, Ostergaard P, Pontikos N, Robson AG, Webster AR, Hogg CR, Wright GA, Henderson RHH, Martin CA, Jackson AP, Mansour S, Moore AT, Michaelides M. Clinical and Molecular Characterization of Familial Exudative Vitreoretinopathy Associated With Microcephaly. Am J Ophthalmol. 2019 Nov;207:87-98. doi: 10.1016/j.ajo.2019.05.001. Epub 2019 May 8. PMID: 31077665.
Abstract
Purpose: Familial exudative vitreoretinopathy (FEVR) is a rare finding in patients with genetic forms of microcephaly. This study documents the detailed phenotype and expands the range of genetic heterogeneity.
Design: Retrospective case series.
Methods: Twelve patients (10 families) with a diagnosis of FEVR and microcephaly were ascertained from pediatric genetic eye clinics and underwent full clinical assessment including retinal imaging. Molecular investigations included candidate gene Sanger sequencing, whole-exome sequencing (WES), and whole-genome sequencing (WGS).
Results: All patients had reduced vision and nystagmus. Six were legally blind. Two probands carried bi-allelic LRP5 variants, both presenting with bilateral retinal folds. A novel homozygous splice variant, and 2 missense variants were identified. Subsequent bone density measurement identified osteoporosis in one proband. Four families had heterozygous KIF11 variants. Two probands had a retinal fold in one eye and chorioretinal atrophy in the other; the other 2 had bilateral retinal folds. Four heterozygous variants were found, including 2 large deletions not identified on Sanger sequencing or WES. Finally, a family of 2 children with learning difficulties, abnormal peripheral retinal vasculogenesis, and rod-cone dystrophy were investigated. They were found to have bi-allelic splicing variants in TUBGCP6. Three families remain unsolved following WES and WGS.
Conclusions: Molecular diagnosis has been achieved in 7 of 10 families investigated, including a previously unrecognized association with LRP5. WGS enabled molecular diagnosis in 3 families after prior negative Sanger sequencing of the causative gene. This has enabled patient-specific care with targeted investigations and accurate family counseling.
