Chi squared values obtained in the transmission disequilibrium test (TDT) for the transmission of key HLA Class 2 haplotypes to affected offspring. Bars to the right of the Y-axis show preferential transmission and bars to the left of the Y-axis show preferential nontransmission. The haplotype DR3-DQB1*0201 was preferentially transmitted to offspring affected by T1D, AITD, or both, while the DR4-DQB1*0302 haplotype was specific for T1D (* P < 0.05, **P < 0.01, *** P < 0.001).