Inner retinal dystrophy in a patient with biallelic sequence variants in BRAT1

Mutations in the BRCA1-associated protein required for the ataxia telangiectasia mutated (ATM) activation-1 (BRAT1) gene cause lethal neonatal rigidity and multifocal seizure syndrome characterized by rigidity and intractable seizures and a milder phenotype with intellectual disability, seizures, nonprogressive cerebellar ataxia or dyspraxia, and cerebellar atrophy. To date, nystagmus, cortical visual impairment, impairment of central vision, optic nerve hypoplasia, and optic atrophy have been described in this condition. This article describes the retinal findings in a patient with biallelic deleterious sequence variants in BRAT1.

Case report of a child with biallelic sequence variants in the BRAT1 gene.

This patient had developmental delay, microcephaly, nystagmus, and esotropia, and full-field electroretinography (ERG) revealed an inner retinal dystrophy. She was found on exome sequencing to have compound heterozygous sequence variants in the BRAT1 gene: one maternally inherited frameshift variant (c.294dupA, predicting p.Leu99Thrfs*92), which has previously been reported, and one paternally inherited novel missense variant (c.803G>A, p.Arg268His), which is likely to affect protein function.

Biallelic sequence variants in BRAT1 have been reported to cause a variety of ocular and systemic manifestations, but to our knowledge, this is the first report of inner retinal dysfunction manifest as selective loss of full-field ERG scotopic and photopic b-wave amplitudes.