Gimap5 wasidentified as the lyp gene in theBBDP rat through a frameshift mutation and premature truncation of the Gimap5protein [2, 6]and can be rescued in a P1-derived artificial chromosome (PAC) transgenic rat [7].However, potential contributions to lymphopenia and/or T1D from the other Gimap genes are still unknown. The gene discussed is GIMAP5; the disease is lymphopenia.