title: Allele *1 of HS1.2 enhancer associates with selective IgA deficiency and IgM concentration.
abstract: Selective IgA deficiency (IGAD) is the most common primary immunodeficiency, yet its pathogenesis is elusive. The IG (heavy) H chain human 3' Regulatory Region harbors three enhancers and has an important role in Ig synthesis. HS1.2 is the only polymorphic enhancer of the 3' RRs. We therefore evaluated HS1.2 allelic frequencies in 88 IGAD patients and 101 controls. Our data show that IGAD patients have a highly significant increase of homozygousity of the allele *1 (39% in the IGAD patients and 15% in controls), with an increase of 2.6-fold. Allele *4 has a similar trend of allele *2, both showing a significant decrease of frequency in IGAD. No relationship was observed between allele *1 frequencies and serum levels of IgG. However, allele *1 was associated in IGAD patients with relatively low IgM levels (within the 30th lowest percentile of patients). The HS1.2 polymorphism influences Ig seric production, but not IgG switch, in fact 30th lowest or highest percentile of IgG in patients did not associate to different frequencies of HS1.2 alleles. The control on normal healthy subjects did not correlate high or low levels of IgM or IgG with HS1.2 allelic frequence variation. Overall our candidate gene approach confirms that the study of polymorphisms in human diseases is a valid tool to investigate the function of these Regulatory Regions that confers multiple immune features.
authors.affiliation: Terry Fox Laboratory, British Columbia Cancer Research Centre, Vancouver, BC, Canada.
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Giambra
authors.forename: Rossella
authors.initials: R
authors.lastname: Cianci
authors.forename: Serena
authors.initials: S
authors.lastname: Lolli
authors.forename: Claudia
authors.initials: C
authors.lastname: Mattioli
authors.forename: Giacomo
authors.initials: G
authors.lastname: Tampella
authors.forename: Marco
authors.initials: M
authors.lastname: Cattalini
authors.forename: Sebnem S
authors.initials: SS
authors.lastname: Kilic
authors.forename: Franco
authors.initials: F
authors.lastname: Pandolfi
authors.forename: Alessandro
authors.initials: A
authors.lastname: Plebani
authors.forename: Domenico
authors.initials: D
authors.lastname: Frezza
mesh_terms: D024509:3' Flanking Region / Q000276:immunology; D000293:Adolescent; D000483:Alleles; D001483:Base Sequence; D002648:Child; D002675:Child, Preschool; D004742:Enhancer Elements, Genetic / Q000276:immunology*; D005260:Female; D005787:Gene Frequency / Q000276:immunology; D006801:Humans; D017098:IgA Deficiency / Q000097:blood / Q000235:genetics* / Q000276:immunology*; D007074:Immunoglobulin G / Q000097:blood; D007143:Immunoglobulin Heavy Chains / Q000235:genetics; D007075:Immunoglobulin M / Q000097:blood* / Q000235:genetics; D007134:Immunoglobulin Switch Region / Q000235:genetics; D008297:Male; D008969:Molecular Sequence Data; D012045:Regulatory Sequences, Nucleic Acid / Q000276:immunology; D055815:Young Adult
chemical_list: D007074:Immunoglobulin G; D007143:Immunoglobulin Heavy Chains; D007075:Immunoglobulin M