Genetic markers on chromosome 19p and prenatal diagnosis of HLA class II-deficient combined immunodeficiency

HLA class II-deficient combined immunodeficiency (CID) is an inherited disease characterized by a total lack of HLA class II gene expression, due to a regulatory defect affecting these genes. In the family investigated the disease phenotype occurs parallel to an abnormal structural feature of the CD23 antigen. We sequenced parts of the FCER2 gene coding for CD23 and found a restriction fragment length polymorphism (RFLP) that cosegregates with the disease. Analysis of recombinant haplotypes by microsatellites mapping to the chromosomal region 19p13.3 suggests that the disease locus maps between FCER2 and the microsatellite marker D19S424, probably close to D19S216 and D19S177. These data may offer the possibility of a rapid and early prenatal diagnosis of a subgroup of patients with HLA class II-deficient CID.