Novel Mutation in BEST1 Associated with Atypical Best Vitelliform Dystrophy

Bilateral, Solitary, Extramacular Vitelliform Retinal Lesions in a Patient With Best Disease

Purpose:

This work describes the first published case of Best vitelliform macular dystrophy (BVMD) with bilateral, solitary, extramacular retinal lesions.

Methods:

A case report is presented.

Results:

An 8-year-old girl with a family history of BVMD was referred for suspicious peripheral retinal lesions. Multimodal imaging disclosed bilateral, solitary, extramacular lesions consistent with the vitelliform lesions found in BVMD. There were no abnormalities in the macula.

Conclusions:

This is the first documented case of solitary, bilateral, extramacular vitelliform lesions in BVMD.

A novel mutation of BEST1 gene in Best disease

PURPOSE

To describe a new genetic variation of BEST1 gene in Best vitelliform macular dystrophy.

METHODS

A patient with bilateral multiple retinal yellowish lesions at the posterior pole underwent fluorescein angiography, fundus autofluorescence, optical coherence tomography, electrooculogram and blood sample for genetic testing.

RESULTS

A diagnosis of a Best vitelliform macular dystrophy was made. Heterozygous mutation c.76G > A (p.Gly26Ser) in exon 2 of the BEST1 gene was found.

CONCLUSION

These findings contribute to expand the mutation spectrum of BEST1 gene.

Atypical presentation of Best Disease

CLINICAL CASE

A 43-year-old man was treated for reduced visual acuity, initially attributed to strabismic amblyopia. On fundus examination, bilateral neurosensory detachments (NSD) were observed in posterior pole, surrounded by deposits of lipofuscin. His 3-year-old son was also examined and circumscribed NSD was observed with the presence of pseudohypopyon in OD and a fibrosis scar in OS. The Arden ratio were decreased in electrooculography (EOG) in both patients, and genetic studies revealed a single mutation of the BEST1 gene.

DISCUSSION

The existence of extensive bilateral NSD may be an unusual form of presentation of Best disease. Family history, EOG, and genetic study supported this diagnosis.

Genetic variations in Bestrophin‑1 and associated clinical findings in two Chinese patients with juvenile‑onset and adult‑onset best vitelliform macular dystrophy

Best vitelliform macular dystrophy (BVMD) is a hereditary retinal disease characterized by the bilateral accumulation of large egg yolk‑like lesions in the sub‑retinal and sub‑retinal pigment epithelium spaces. Macular degeneration in BVMD can begin in childhood or adulthood. The variation in the age of onset is not clearly understood. The present study characterized the clinical characteristics of two Chinese patients with either juvenile‑onset BVMD or adult‑onset BVMD and investigated the underlying genetic variations. A 16‑year‑old male (Patient 1) was diagnosed with juvenile‑onset BVMD and a 43‑year‑old female (Patient 2) was diagnosed with adult‑onset BVMD. Comprehensive ophthalmic examinations were performed, including best‑corrected visual acuity, intraocular pressure, slit‑lamp examination, fundus photography, optical coherence tomography, fundus fluorescein angiography imaging and Espion electrophysiology. Genomic DNA was extracted from peripheral blood leukocytes collected from these patients, their family members, and 200 unrelated subjects within in the same population. The 11 exons of the bestrophin‑1 (BEST1) gene were amplified by polymerase chain reaction and directly sequenced. Both patients presented lesions in the macular area. In Patient 1, a heterozygous mutation c.903T>G (p.D301E) in exon 8 of the BEST1 gene was identified. This mutation was not present in any of the unaffected family members or the normal controls. Polymorphism phenotyping and the sorting intolerant from tolerant algorithm predicted that the amino acid substitution D301E in bestrophin‑1 protein was damaging. In Patient 2, a single nucleotide polymorphism c.1608C>T (p.T536T) in exon 10 of the BEST1 gene was identified. These findings expand the spectrum of BEST1 genetic variation and will be valuable for genetic counseling and the development of therapeutic interventions for patients with BVMD.