The transmission/disequilibrium test (TDT) is one of the most popularly used methods in family-based association studies. Based on a set of case-parent triad families, the TDT extracts information of transmission and nontransmission (TNT) of a particular marker allele from heterozygous parents to create a family-based case control design. Such a type information though does provide some information for association between a maker and a disease, it may not the only resource of association information contained in the triad families. According to this idea in this thesis we thus introduce another association information, the similarity into the testing procedure. We use the existing combination methods to combine information of the TNT and similarity to obtain two new association tests. Simulation studies show that our methods outperform the TDT in some situations.