A genetically modified rodent animal comprising in its genome a. a nucleic acid encoding a chimeric Clqa polypeptide, wherein the chimeric Clqa polypeptide comprises (i) a globular head domain that is at least 90% identical to the globular head domain of a human Clqa polypeptide wherein the globular head domain of a human Clqa polypeptide comprises amino acids 108-245 of SEQ ID NO: 4, and (ii) an N-terminal stalk-stem region that is at least 90% identical to the N-terminal stalk-stem region of an endogenous rodent Clqa polypeptide; b. a nucleic acid encoding a chimeric Clqb polypeptide, wherein the chimeric Clqb polypeptide comprises (i) a globular head domain that is at least 90% identical to the globular head domain of a human Clqb polypeptide wherein the globular head domain of a human Clqb polypeptide comprises amino acids 115-251 of SEQ ID NO: 5, and (ii) an N-terminal stalk-stem region that is at least 90% identical to the N-terminal stalk-stem region of an endogenous rodent Clqb polypeptide; and c. a nucleic acid encoding a chimeric Clqc polypeptide, wherein the chimeric Clqc polypeptide comprises (i) a globular head domain that is at least 90% identical to the globular head domain of a human Clqc polypeptide wherein the globular head domain of a human Clqc polypeptide comprises amino acids 113-245 of SEQ ID NO: 6, and (ii) an N-terminal stalk-stem region that is at least 90% identical to the N-terminal stalk-stem region of an endogenous rodent Clqc polypeptide; wherein the chimeric Clqa, Clqb and Clqc polypeptides are expressed in the rodent animal and form a functional C1q complex; and wherein the rodent animal does not express a functional endogenous Clqa polypeptide, a functional endogenous Clqb polypeptide, or a functional endogenous Clqc polypeptide. a. a nucleic acid encoding a chimeric Clqa polypeptide, wherein the chimeric Clqa polypeptide comprises (i) a globular head domain that is at least 90% identical to the globular head domain of a human Clqa polypeptide wherein the globular head domain of a human Clqa polypeptide comprises amino acids 108-245 of SEQ ID NO: 4, and (ii) an N-terminal stalk-stem region that is at least 90% identical to the N-terminal stalk-stem region of an endogenous rodent Clqa polypeptide; b. a nucleic acid encoding a chimeric Clqb polypeptide, wherein the chimeric Clqb polypeptide comprises (i) a globular head domain that is at least 90% identical to the globular head domain of a human Clqb polypeptide wherein the globular head domain of a human Clqb polypeptide comprises amino acids 115-251 of SEQ ID NO: 5, and (ii) an N-terminal stalk-stem region that is at least 90% identical to the N-terminal stalk-stem region of an endogenous rodent Clqb polypeptide; and c. a nucleic acid encoding a chimeric Clqc polypeptide, wherein the chimeric Clqc polypeptide comprises (i) a globular head domain that is at least 90% identical to the globular head domain of a human Clqc polypeptide wherein the globular head domain of a human Clqc polypeptide comprises amino acids 113-245 of SEQ ID NO: 6, and (ii) an N-terminal stalk-stem region that is at least 90% identical to the N-terminal stalk-stem region of an endogenous rodent Clqc polypeptide; wherein the chimeric Clqa, Clqb and Clqc polypeptides are expressed in the rodent animal and form a functional C1q complex; and wherein the rodent animal does not express a functional endogenous Clqa polypeptide, a functional endogenous Clqb polypeptide, or a functional endogenous Clqc polypeptide. <EOS>