Whilst it is possible that 38 kDa bands detected on autoradiographs after immunoprecipitation by antibodies in Type 1 diabetes sera may include proteins other than Tspan7, a more likely explanation is that some Tspan7 autoantibody epitopes may not be accessible on the recombinant antigen, either as a consequence of steric hindrance by the luciferase tag or because of issues with the conformation of Tspan7 when expressed as a recombinant protein; recombinant protein hyperexpression in mammalian cell expression systems may result in significant protein misfolding. The gene discussed is TSPAN7; the disease is type 1 diabetes mellitus.