Environment-gene interaction in multiple sclerosis: human herpesvirus 6 and MHC2TA.
Multiple sclerosis (MS) is an inflammatory disorder affecting the central nervous system, in which both genetic and environmental factors interact. Among these environmental contributors, herpesvirus has been proposed as an important etiologic factor. CIITA is a transcription factor controlling the expression of MHC class II genes, the main genetic determinants of MS susceptibility. This gene has been described as a target of the immunoevasive strategies, and it is therefore an attractive candidate gene to be at the genetic-viral crossroads. Two polymorphisms in MHC2TA gene (rs4,774G/C and rs3,087,456A/G) were studied in two groups: one in 22 multiple sclerosis patients with active human herpes virus 6 (HHV-6A) replication (HHV-6A-positive), and the other of 77 patients with no detectable HHV-6A active infection (HHV-6A-negative); a Spanish healthy control group (n = 520) was also included as external control. An association of the rs4,774C allele with the HHV-6A-positive group was found when compared with the HHV-6A-negative (47.7% vs 18.8%, p = 0.0001; odds ratio = 3.94) and also with the control group (47.7% vs 25.5%, p = 0.001, odds ratio = 2.67). No significant differences were observed between HHV-6A-negative subjects and healthy controls. Our data suggest that a strong gene-environment interaction occurs between HHV-6A active replication and MHC2TA rs4,774C or another polymorphism in tight linkage disequilibrium with it. Besides, this report indicates that when patients are grouped based upon a well-defined molecular event, complex diseases may reveal themselves as being constituted by distinct entities in which some genes may have a strong influence.
Martínez
Alfonso
A
Clinical Immunology Department, Hospital Clínico San Carlos, Madrid, Spain. alfmdoncel@terra.es
Alvarez-Lafuente
Roberto
R
Mas
Ana
A
Bartolomé
Manuel
M
García-Montojo
Marta
M
de Las Heras
Virginia
V
de la Concha
Emilio G
EG
Arroyo
Rafael
R
Urcelay
Elena
E
D000293:Adolescent; D000328:Adult; D002648:Child; D005260:Female; D020022:Genetic Predisposition to Disease; D015654:Herpesvirus 6, Human / Q000302:isolation & purification / Q000502:physiology*; D006801:Humans; D008297:Male; D009103:Multiple Sclerosis / Q000235:genetics* / Q000276:immunology / Q000821:virology; D009687:Nuclear Proteins / Q000235:genetics* / Q000276:immunology; D020641:Polymorphism, Single Nucleotide; D019349:Roseolovirus Infections / Q000276:immunology / Q000821:virology*; D015534:Trans-Activators / Q000235:genetics* / Q000276:immunology
C083728:MHC class II transactivator protein; D009687:Nuclear Proteins; D015534:Trans-Activators