Characterisation of psoriasis susceptibility locus 6 (PSORS6) in patients with early onset psoriasis and evidence for interaction with PSORS1.
BACKGROUND
Psoriasis is a genetically complex, chronic inflammatory skin disease. The authors have previously identified a susceptibility locus on chromosome 19p13 (PSORS6).


RESULTS
In a follow-up linkage disequilibrium (LD) study in an independent family based cohort, the authors found evidence for association to a newly discovered microsatellite at this locus (D19SPS21, p<5.3x10(-5)). An LD based association scan in 300 trios revealed association to several single, single nucleotide polymorphisms (SNPs) in one LD block. When the authors stratified this cohort for carrying the PSORS1 risk allele at the HLA-C locus, evidence for association became much stronger at single SNP and haplotype levels (p values between 1.0x10(-4) and 8.0x10(-4)). In a replication study of 1114 patients and 937 control individuals, evidence for association was also observed after stratification to the PSORS1 risk allele. In both study groups, logistic regression showed evidence for interaction between the risk alleles at PSORS1 and PSORS6. Best p values for rs12459358 in both study groups remained significant after correction for multiple testing. The associated LD block did not comprise any known genes. Interestingly, an adjacent gene, MUC16, coding for a large glycosylated protein expressed in epithelia and of unknown function, could be shown to be also expressed in tissues relevant for pathogenesis of psoriasis such as skin and thymus. Immunohistochemical analyses of skin revealed focal staining for MUC16 in suprabasal epidermal cells. Further functional studies are required to clarify its potential role in psoriasis and identify the causal variant(s) at this locus.


CONCLUSIONS
The data establish PSORS6 as a confirmed psoriasis susceptibility locus showing interaction with PSORS1.
Hüffmeier
U
U
Institute of Human Genetics, University Hospital Erlangen, University of Erlangen-Nuremberg, 91054 Erlangen, Germany. reis@humgenet.uni-erlangen.de
Lascorz
J
J
Becker
T
T
Schürmeier-Horst
F
F
Magener
A
A
Ekici
A B
AB
Endele
S
S
Thiel
C T
CT
Thoma-Uszynski
S
S
Mössner
R
R
Reich
K
K
Kurrat
W
W
Wienker
T F
TF
Traupe
H
H
Reis
A
A
D000293:Adolescent; D000328:Adult; D017668:Age of Onset; D018394:CA-125 Antigen / Q000378:metabolism; D016009:Chi-Square Distribution; D005787:Gene Frequency; D020022:Genetic Predisposition to Disease; D006239:Haplotypes; D006801:Humans; D007150:Immunohistochemistry; D015810:Linkage Disequilibrium; D008297:Male; D008565:Membrane Proteins / Q000378:metabolism; D018895:Microsatellite Repeats; D008875:Middle Aged; D011506:Proteins / Q000235:genetics* / Q000378:metabolism; D011565:Psoriasis / Q000235:genetics*
D018394:CA-125 Antigen; C451759:MUC16 protein, human; D008565:Membrane Proteins; C484393:PSORS1C1 protein, human; D011506:Proteins