title: New C1q mutation in a Tunisian family.
abstract: Hereditary C1q deficiency (C1qD) is the most penetrant genetic factor predisposing to the development of lupus pathology with more than 93% of C1q deficient patients developing this autoimmune pathology throughout their life. It is a rare autosomal recessive deficiency, with only 67 cases reported so far including one Tunisian girl who died at the age of three from complications resulting from severe systemic lupus erythematosus. Although C1qD was confirmed in the serum of this patient using C1q ELISA and classical pathway specific functional assays, no DNA sample had been obtained from this patient. Here we report the analysis of sera and DNA of members of this patient's closer family. Our analysis identified a homozygous mutation within the gene encoding the C-chain of C1q leading to a deficiency of C1q in an older sister of our original patient. This mutation, termed g.5580G4C, represents a single basepair substitution in exon 1 of the C1q C chain gene which changes the codon of Gly61 to Arg 61. Amongst the other 14 mutations leading to C1qD, g.5580G4C represents the first reported transversion leading to human C1qD.
authors: Laboratoire d'immunologie, Hôpital la Rabta, 1007 Tunis, Tunisia.
authors: Hend
authors: H
authors: Jlajla
authors: Laboratoire d'immunologie, Hôpital la Rabta, 1007 Tunis, Tunisia. Electronic address: maryam_kallel@yahoo.com.
authors: Maryam Kallel
authors: MK
authors: Sellami
authors: Laboratoire d'immunologie, Hôpital Charles Nicolle, 1007 Tunis, Tunisia.
authors: Imen
authors: I
authors: Sfar
authors: Laboratoire d'immunologie, Hôpital la Rabta, 1007 Tunis, Tunisia.
authors: Lilia
authors: L
authors: Laadhar
authors: Laboratoire d'immunologie, Hôpital la Rabta, 1007 Tunis, Tunisia.
authors: Yousr
authors: Y
authors: Zerzeri
authors: Service de Pédiatrie, Hôpital La Rabta, 1007 Tunis, Tunisia.
authors: Mohamed Slim
authors: MS
authors: Abdelmoula
authors: Laboratoire d'immunologie, Hôpital Charles Nicolle, 1007 Tunis, Tunisia.
authors: Yousr
authors: Y
authors: Gorgi
authors: Service de Pédiatrie, Hôpital La Rabta, 1007 Tunis, Tunisia.
authors: Marie-Françoise
authors: MF
authors: Dridi
authors: Laboratoire d'immunologie, Hôpital la Rabta, 1007 Tunis, Tunisia.
authors: Sondes
authors: S
authors: Makni
mesh_terms: D000293:Adolescent; D002675:Child, Preschool; D015922:Complement C1q / Q000235:genetics* / Q000378:metabolism; D004252:DNA Mutational Analysis; D018450:Disease Progression; D005190:Family; D017809:Fatal Outcome; D005260:Female; D005787:Gene Frequency; D020022:Genetic Predisposition to Disease; D005838:Genotype; D006461:Hemolysis / Q000235:genetics; D006801:Humans; D008178:Lupus Erythematosus, Cutaneous / Q000235:genetics* / Q000276:immunology; D008180:Lupus Erythematosus, Systemic / Q000235:genetics* / Q000276:immunology; D009154:Mutation / Q000235:genetics*; D010375:Pedigree; D011110:Polymorphism, Genetic; D035781:Siblings; D014416:Tunisia
chemical_list: D015922:Complement C1q
keywords: AA; Autoimmunity; C1q deficiency; C1qD; Classical pathway; Complement; LE; Mutation; Primary immunodeficiency; SLE; amino acid; lupus erythematosus; systemic lupus erythematosus