New genetic feature associated with fundus albipunctatus: case series of two Spanish children with LRAT gene mutation

To describe the genetic mutation and its action mechanism in patients with compatible diagnosis of fundus albipunctatus (FAP).

We describe the clinical evolution and genetic findings of two female Spanish children of 14 and 16 years old who have been followed at the children's hospital Sant Joan de Déu (Barcelona, Spain). Nyctalopia without detectable field constriction was the initial symptom. Retinal fundus was compatible with FAP or retinitis punctata albescens (RPA). We have registered ophthalmological examination from each visit, including visual acuity, visual field assessment, wide-field fundoscopy imaging, fundus autofluorescence and optical coherence tomography. Full-field electroretinogram (ERG) was also performed. DNA sampling was analysed by next-generation sequency (NGS).

Compound heterozygous pathogenic variants in the LRAT gene were identified in both children. Interestingly, these were the same two pathogenic variants, despite the families being unrelated. No additional genetic alterations were found that could explain the disease in our patients.

To the best of our knowledge, up to the present time, only a single clinical case involving a genetic variant in the LRAT gene leading to an FAP phenotype has been reported in the literature. LRAT genetic variants, despite their low frequency in clinical practice, seem to lead to a FAP-like phenotype, in addition to their established association with Leber congenital amaurosis (LCA) and Early Onset Severe Retinal Dystrophy (EOSRD).