Novel Potentially Pathogenic Variants in TBC1D32 Cause Non-syndromic Rod-Cone Degeneration

Inherited retinal degenerations (IRDs) are a group of Mendelian disorders characterized by progressive dysfunction and loss of rod and/or cone photoreceptors. The most common IRD is rod-cone degeneration (RCD, also known as retinitis pigmentosa), which starts with rod photoreceptor cell loss and eventually can lead to cone photoreceptor dysfunction and death. Thus, RCD initially manifests with loss of peripheral vision and night blindness and can lead to central vision loss as well. RCD is genetically heterogeneous with mutations in over 90 genes that have been so far associated with this disease. Recently, TBC1D32 has been proposed as a novel recessive RCD gene, as rare bi-allelic pathogenic variants were found in three unrelated European families. In this report, we describe a fourth RCD family of European descent carrying two novel mutations in TBC1D32, thus providing secondary evidence for this recent association.