title: Frequency in Spanish population of familial complement factor 2 type I deficits and associated HLA haplotypes.
abstract: We present two familial cases of complement factor 2 (C2) type I deficiency. Probands had experienced severe pyogenic bacteria infections in childhood and had undetectable levels of C2 and very low level of CH50. Both children were homozygous for the deletion of 28 bp in exon 6 of the C2 gene. Human leukocyte antigen (HLA) typing in family 1 had the commonly reported associations, but family 2 demonstrated a new association of the mutated C2 gene to HLA-A*3101, -Cw*0602, -B*1801, and -DRB1*0901. In addition, for the first time, the frequency of the 28-bp deletion of C2 and its HLA haplotypic associations have been analyzed in a sample of the Spanish population containing 790 haplotypes and 105 phenotypes. Cw*0602 is frequently found in Spanish haplotypes linked to the C2 mutated gene instead of the commonly reported -Cw*1203. The presence of heterozygous or homozygous individuals for the C2 deletion with low levels of IgD in both families supports the existence of a putative dominant susceptibility gene for IgD deficiency in haplotype HLA-B18, -S042, and -DR2. The frequency of the C2 28-bp deletion in heterozygosis is 1.4% (gene frequency 0.007) in Spanish healthy controls, similar to that reported in other white populations.
authors.affiliation: Servicio de Inmunología, Hospital Universitario Doce de Octubre, Madrid, Spain. scalleja.hdoc@salud.madrid.org
authors.forename: S Calleja
authors.initials: SC
authors.lastname: Antolín
authors.forename: M J
authors.initials: MJ
authors.lastname: Del Rey Cerros
authors.forename: E Mancebo
authors.initials: EM
authors.lastname: Sierra
authors.forename: D Oliver
authors.initials: DO
authors.lastname: Miñarro
authors.forename: J
authors.initials: J
authors.lastname: Clemente
authors.forename: L Allende
authors.initials: LA
authors.lastname: Martínez
authors.forename: P Varela
authors.initials: PV
authors.lastname: Peña
authors.forename: M J Castro
authors.initials: MJ
authors.lastname: Panete
authors.forename: P Morales
authors.initials: PM
authors.lastname: Pérez
authors.forename: E
authors.initials: E
authors.lastname: Paz-Artal
mesh_terms: D002648:Child; D002675:Child, Preschool; D003175:Complement C2 / Q000172:deficiency / Q000235:genetics*; D005260:Female; D005787:Gene Frequency; D005838:Genotype; D006680:HLA Antigens / Q000235:genetics*; D015234:HLA-A Antigens / Q000235:genetics; D015235:HLA-B Antigens / Q000235:genetics; D015236:HLA-C Antigens / Q000235:genetics; D006684:HLA-DR Antigens; D059811:HLA-DRB1 Chains; D006239:Haplotypes; D006579:Heterozygote; D006801:Humans; D008297:Male; D009154:Mutation; D010375:Pedigree; D010641:Phenotype; D013030:Spain
chemical_list: D003175:Complement C2; D006680:HLA Antigens; D015234:HLA-A Antigens; C506273:HLA-A*31:01 antigen; D015235:HLA-B Antigens; D015236:HLA-C Antigens; C491620:HLA-C*06:02 antigen; D006684:HLA-DR Antigens; D059811:HLA-DRB1 Chains; C487381:HLA-DRB1*09:01 antigen