Identification of ΔCFHR1-ΔCFHR4 deletion by MLPA. (A) Nonhomologous recombination event between homologous regions of the CFHR1 and CFHR4 genes that could have resulted in the ΔCFHR1-ΔCFHR4 deletion. (B) Electropherograms of the MLPA analyses showing heterozygous and homozygous deletions in patients with aHUS. (C) Frequency of the novel ΔCFHR1-ΔCFHR4 deletion in control persons and patients.