Chronic course of a hemolytic uremic syndrome caused by a deficiency of factor H-related proteins (CFHR1 and CFHR3)

A 36-year-old patient complained of progressing fatigue, lack of appetite, and weakness for a few weeks, for which he had been using paracetamol (acetaminophen) intermittently. He was referred to our center from another hospital with hemolysis, thrombocytopenia, and acute renal failure (ARF). On admission, the patient did not complain of any specific additional symptoms. Besides paracetamol, he had not received any other medication. The patient reported flu-like symptoms 3 months before admission. The family history was unremarkable. Physical examination revealed a pale-looking patient (180 cm; 81 kg) with icteric sclerae. He was tachycardic (110 heart beats per min) and had elevated blood pressure (155/90mmHg). No other physical abnormalities were detectable. Laboratory investigations are depicted in Table 1. Specific analyses: von Willebrand factor cleavage protease activity 31% (40-120%), von Willebrand Factor Multimere negative, antibodies to von Willebrand Factor cleavage protease negative, factor H 614 mgl(-1) (345-590 mgl(-1)). Western blot analyses with patient's serum revealed the presence of complement factor H (CFH) and complement factor H-like protein 1 (CFHL1), but no detectable levels of complement factor H-related proteins 1 and 3 (CFHR1 and CFHR3) (Figure 1a). Antibodies to CFHR1 were negative. Genetic analyses 1 showed no CFH mutation, but revealed homozygous deletion of a 83 kb genomic fragment representing CFHR3 and CFHR1 (Figure 1b). Kidneys were of normal size with increased density by ultrasound examination. Electrocardiography revealed ischemic changes posteroseptally, and hypertrophy of the left ventricle was diagnosed by echocardiography.