Two variants of the ferredoxin reductase (FDXR) causing isolated retinitis pigmentosa

Objective: The FDXR gene encodesferredoxin reductase, which is a mitochondrial membrane protein and plays a role in Fe-S cluster synthesis. Loss of function in this gene causes intracellular iron accumulation, leading to dysfunction, especially in nervous system cells. To date, 46 patients with biallelic FDXR variants have been reported. While optic atrophy was a common finding in most of the patients, it was found that many neurological findings were also accompanied. Method: Two siblings from an unrelated Turkish family and their parents were included. DNA was isolated from the patient’s blood sample. Whole exome sequencing was performed using next-generation DNA sequencing. Results: We described two siblings with the same compound heterozygous variants, but with phenotypically different characteristics. While ataxia, opticatrophy, and minor dysmorphic findings were present in one sibling, we did not detect any finding other than subclinical retinal dystrophy in the other sibling. Conlusion: Many patients described in the literature have also been reported to show wide phenotypic variability. We would like to report these patients to contribute to the genotype phenotype relationship of the disease and to create resources for future gene therapies.