Association and linkage studies of the 20q11.2 region (GRD-2 locus) with Graves' disease in the Tunisian population.
OBJECTIVE
A genome-wide screen has shown linkage to the GRD-2 locus in Graves' disease (GD). Furthermore, a positional candidate gene maps to this locus; the CD40 gene has been reported to be associated and may predispose to the disease. The aim of this study was to replicate/reject the GRD-2 and to determine if the single nucleotide polymorphism (SNP) of the CD40 (CD40 C/T-1) confers susceptibility to GD.


METHODS
The present study examined a dataset of 11 families with GD using 10 microsatellite markers and a case-control study consisting of 76 sporadic GD patients and 66 healthy subjects to determine the implication of the GRD-2. Both non-parametric linkage and association tests were performed. Genotyping of the CD40 C/T-1 was carried out using a polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP).


RESULTS
The intrafamilial association and the case-control study showed no association between CD40 C/T-1 and GD. In addition, a high percentage of the C allele (96.9%) of CD40 SNP among control data was observed. The linkage analyses showed that the highest non-parametric LOD score was 1.67 at the D20S119 marker and the maximum attainable LOD score was 1.66. This result provides interesting evidence for linkage between GRD-2 and GD.


CONCLUSIONS
The CD40 gene seems to be not associated with GD in the Tunisian population, whereas the GRD-2 locus could harbour other candidate gene(s) to the genetic susceptibility of GD.
Makni
K
K
Centre de Biotechnologie de Sfax, Sfax, Tunisia. kaouthar2005@gmail.com
Hadj Kacem
H
H
Rebaï
A
A
Abid
M
M
Ayadi
H
H
D000483:Alleles; D019013:CD40 Antigens / Q000097:blood / Q000235:genetics*; D016022:Case-Control Studies; D002890:Chromosomes, Human, Pair 20; D005192:Family Health; D005787:Gene Frequency; D020022:Genetic Predisposition to Disease / Q000453:epidemiology; D005820:Genetic Testing; D006111:Graves Disease / Q000097:blood / Q000453:epidemiology / Q000235:genetics*; D006801:Humans; D015810:Linkage Disequilibrium / Q000276:immunology; D008126:Lod Score; D018895:Microsatellite Repeats; D012150:Polymorphism, Restriction Fragment Length; D020641:Polymorphism, Single Nucleotide; D014416:Tunisia