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BIBTEX RIS

Deficiency of the Human Complement Regulatory Protein Factor H Associated with Low Levels of Component C9

2008; Wiley; Volume: 68; Issue: 4 Linguagem: Inglês

10.1111/j.1365-3083.2008.02152.x

1365-3083

Dayseanne Araújo Falcão, Edimara S. Reis, Danielle Paixão-Cavalcante, Mariane Tami Amano, Maria Isabel Delcolli, M. P. C. Florido, José Antônio Tavares de Albuquerque, Dewton de Moraes Vasconcelos, António Duarte, Anete Sevciovic Grumach, Lourdes Isaac,

Blood groups and transfusion

Abstract We identified a 4‐year‐old Brazilian boy from a family of Japanese descent and history of consanguinity, who suffered from severe recurrent pneumonia. He carries factor H (FH) deficiency associated with reduced levels of component C9 and low serum levels of C3 and factor B. His mother also presented low levels of these proteins and factor I, while his father and sister had only lower levels of FH. Western blot assays confirmed the complete absence of FH and FHL‐1 polypeptides in this patient. Sequencing of the proband’s FH cDNA revealed a homozygous G453A substitution, encoding an Arg 127 His change. His mother, father and sister are heterozygous for this substitution. Despite the absence of FH in the plasma, this protein was detected in the patient’s fibroblasts, suggesting that Arg 127 may be important for FH secretion. Low concentrations of C9 were detected in the proband serum but no mutations in the patient’s C9 gene or promoter have been identified, suggesting that this is a consequence of uncontrolled complement activation and high C9 consumption.