H. Melinaldana et al., MAJOR HISTOCOMPATIBILITY COMPLEX GENES IN A MEXICAN FAMILY WITH DEFICIENCY OF THE 2ND COMPONENT OF THE COMPLEMENT-SYSTEM, Revista de Investigacion Clinica, 48(4), 1996, pp. 307-309
Hereditary deficiency of the second component of the complement system
is an uncommon condition that has been reported so far mostly in Cauc
asians. We describe a Mexican patient with undetectable C2 levels and
absence of complement hemolytic activity. Major histocompatibility com
plex (MHC) genes in his family showed that the proband had the MHC hap
lotypes HLA-A25, B18, DR2, DQ1, SQ042/HLA-A24, B18, DR2, DQ1, SQ042. A
strong genetic linkage of the deficiency of the second component of t
he complement gene and the HLA antigens A25, B18, and DR2, is well est
ablished in Caucasian populations. This suggests that the probable ori
gin of the deficiency in our patient was admixture with Caucasian ance
stors.