TRIM21 and retinitis pigmentosa 1: Given the seronegative clinical features (normal IgG level and negative anti-Ro/SSA) in RP patients, we speculate that the CLEC1L, which encodes a member of the C-type lectin-like domain superfamily, expressed on memory B cells, may contribute to recognizing endogenous and exogenous ligands for cellular and inflammatory responses by serving as pattern recognition receptors.