Frequency in Spanish population of familial complement factor 2 type I deficits and associated HLA haplotypes.
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.
Antolín
S Calleja
SC
Servicio de Inmunología, Hospital Universitario Doce de Octubre, Madrid, Spain. scalleja.hdoc@salud.madrid.org
Del Rey Cerros
M J
MJ
Sierra
E Mancebo
EM
Miñarro
D Oliver
DO
Clemente
J
J
Martínez
L Allende
LA
Peña
P Varela
PV
Panete
M J Castro
MJ
Pérez
P Morales
PM
Paz-Artal
E
E
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
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