Homozygosity for a novel mutation in the C1q c chain gene in a Turkish family with hereditary C1q deficiency

Hereditary complete deficiency of complement component c1q is associated with a high prevalence of systemic lupus erythematosus and increased susceptibility to severe recurrent infections. an 11-year-old girl was screened for immunodeficiency due to a history of recurrent meningitis and pneumonia. immunologic studies revealed absence of classic pathway hemolytic activity and undetectable levels of c1q. exon-specific amplification of genomic dna by polymerase chain reaction followed by direct sequence analysis revealed a novel homozygous missense mutation at codon 48 in the c1q c gene causing a glycine-to-arginine substitution affecting the collagen-like region of c1q. no changes were seen in the exons of the a and b chains. the mutation affected both the formation and the secretion of c1q variant molecules. we describe a novel mutation in the c1q c chain gene that leads to an interchange in amino acids resulting in absence of c1q in serum. © 2010 esmon publicidad.