BTNL3 and cranioectodermal dysplasia: As the HV4 is germline-encoded and does not undergo recombination, we hypothesised that variations in the germline-encoded TRGV4-HV4 amino acid sequence could alter the binding of the Vγ4+ γδ T cells to BTNL3 protein in the duodenum, predisposing to CeD.