C1q deficiency in an Inuit family: Identification of a new class of C1q disease-causing mutations

C1q deficiency is a rare condition associated with a systemic lupus erythematosus (SLE)-like syndrome and recurrent infections. Here we present the molecular basis behind C1q deficiency in three sisters of Inuit origin. Initial examination for complement deficiency showed no function of the classica...

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Bibliographic Details
Published in:Clinical Immunology
Main Authors: Marquart, Hanne Vibeke, Schejbel, Lone, Sjöholm, Anders, Mårtensson, Ulla, Nielsen, Susan, Koch, Anders, Svejgaard, Arne, Garred, Peter
Format: Article in Journal/Newspaper
Language:English
Published: Elsevier 2007
Subjects:
Immunology in the medical area
autoimmunity
primary immunodeficiency
mutation
classical pathway
infections
SLE
C1q deficiency
complement
Three Sisters
inuit
Online Access:https://lup.lub.lu.se/record/645857
https://doi.org/10.1016/j.clim.2007.03.547
Description
Summary:C1q deficiency is a rare condition associated with a systemic lupus erythematosus (SLE)-like syndrome and recurrent infections. Here we present the molecular basis behind C1q deficiency in three sisters of Inuit origin. Initial examination for complement deficiency showed no function of the classical complement activation pathway in the patients; the lectin and alternative pathways were intact. No C1q or tow molecular weight Clq was detected in sera and no anti-C1q autoantibodies were found. Sequencing of the C1q genes revealed a novel missense mutation (Gly-Arg) in codon 217 of the B chain. All sisters were homozygous for the mutation: both parents were heterozygous. None of 100 healthy controls carried the mutation. Our findings define a third class of molecular mechanisms behind C1q deficiency, where missense mutations cause a lack of detectable C1q-antigen in serum. (c) 2007 Elsevier Inc. ALL rights reserved.

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