Complement factor I deficiency: a not so rare immune defect: characterization of new mutations and the first large gene deletion.
BACKGROUND
Complement Factor I (CFI) is a serine protease with an important role in complement alternative pathway regulation. Complete factor I deficiency is strongly associated with severe infections. Approximately 30 families with this deficiency have been described worldwide.


METHODS
We have studied five new Spanish families suffering from CFI deficiency. From 19 screened people, 7 homozygous, 10 heterozygous and 2 healthy subjects were identified. Clinical, biochemical and genetic descriptions are included.


RESULTS
Molecular studies demonstrated 4 novel mutations in the screened individuals; amongst them, we describe here the first great gene deletion reported in the CFI locus, which includes full exon 2 and part of the large intron 1.


CONCLUSIONS
CFI deficiency is possibly an underestimated defect and the eventual existence of this deficiency should be tested in those patients exhibiting low C3 and recurrent bacterial infections. We propose a simple diagnostic flowchart to help clinicians in the identification and correct diagnosis of such patients.
Unidad de Inmunología Hospital Universitario La Paz and Hospital La Paz Health Research Institute (IdiPAZ), Madrid, Spain.
María
M
Alba-Domínguez
Alberto
A
López-Lera
Sofía
S
Garrido
Pilar
P
Nozal
Ignacio
I
González-Granado
Josefa
J
Melero
Pere
P
Soler-Palacín
Carmen
C
Cámara
Margarita
M
López-Trascasa
D000328:Adult; D001424:Bacterial Infections / Q000150:complications* / Q000276:immunology; D002648:Child; D002675:Child, Preschool; D003176:Complement C3 / Q000172:deficiency / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D003181:Complement C4 / Q000378:metabolism; D017244:Complement Factor I / Q000172:deficiency / Q000235:genetics*; D005091:Exons; D005190:Family; D005260:Female; D017353:Gene Deletion; D030342:Genetic Diseases, Inborn / Q000150:complications* / Q000175:diagnosis* / Q000235:genetics / Q000276:immunology; D000081208:Hereditary Complement Deficiency Diseases; D006579:Heterozygote; D006720:Homozygote; D006801:Humans; D008297:Male; D009154:Mutation; D010375:Pedigree; D012008:Recurrence; D013030:Spain
D003176:Complement C3; D003181:Complement C4; D017244:Complement Factor I