Most cases of hemolytic uremic syndrome (HUS) are caused by infection with enterohemorrhagic Escherichia coli (EHEC). Genetic defects causing uncontrolled complement activation are associated with the more severe atypical HUS (aHUS). Non-EHEC infections can trigger the disease, however, complement defects predisposing to such infections have not yet been studied. We describe a 2-month-old patient infected with different Gram-negative bacterial species resulting in aHUS. Serum analysis revealed slow complement activation kinetics. Rare variant R229C was found in complement inhibitor vitronectin. Recombinant mutated vitronectin showed enhanced complement inhibition in vitro and may have been a predisposing factor for infection. Our work indicates that genetic changes in aHUS can not only result in uncontrolled complement activation but also increase vulnerability to infections contributing to aHUS.

A 39-year-old woman with demarcated wrinkled areas, histologically characterized by absence of elastic fibers in the middle and upper reticular dermis, is described. Immunoreactivity of vitronectin and amyloid P component, present at the periphery of elastic fibers in normal skin in adults, was absent from the middermis of lesional skin as were orcein stained fibers. C9 neoantigen immunoreactivity, associated with elastic fibers in sun-exposed skin of middle-aged and elderly individuals, was present in conjunction with elastic fibers in papillary and lower reticular dermis in lesional skin but was absent in the middermis. In contrast, a fibrillin immunoreactive network was present throughout the dermis, indicating that the elastin-associated microfibrils are retained in the absence of amorphous elastin in lesional skin of middermal elastolysis.