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ARTHRITIS & RHEUMATISM
Vol. 52, No. 1, January 2005, pp 269–274
DOI 10.1002/art.20777
© 2005, American College of Rheumatology
A Locus on Chromosome 9p Predisposes to a
Specific Disease Manifestation, Acute Anterior Uveitis, in
Ankylosing Spondylitis, a Genetically Complex,
Multisystem, Inflammatory Disease
Tammy M. Martin,
1
Ge Zhang,
2
Jingchun Luo,
2
Li Jin,
2
Trudy M. Doyle,
1
Barbara M. Rajska,
1
Jessica E. Coffman,
1
Justine R. Smith,
1
Matthias D. Becker,
3
Friederike Mackensen,
3
Muhammad A. Khan,
4
Ralph D. Levinson,
5
H. Ralph Schumacher,
6
N. Kevin Wade,
7
James T. Rosenbaum,
1
and John D. Reveille
8
Objective. Uveitis or intraocular inflammation is
a major cause of visual loss. Acute anterior uveitis
(AAU) affects ⬃40% of patients with ankylosing spon-
dylitis (AS) but also affects patients with no evidence of
spondylarthritis. We sought to determine whether a
unique genetic region could be implicated in a specific
manifestation—AAU—of a multisystem, inflammatory,
genetically complex disease, AS.
Methods. Individuals from families multiplex for
AAU were genotyped at 400 markers representing the
ABI PRISM linkage map MD-10, and at the HLA–B,
DRB1, DQA1, DQB1, and DPB1 alleles. Among the
family members with AAU, 76 affected sibpairs were
analyzed (6 without concomitant AS, 12 discordant for
AS, and 58 concordant for AS). Two-point and multi-
point nonparametric linkage analyses were performed,
and 1-parameter allele-sharing model logarithm of odds
(LOD) scores were determined.
Results. As previously reported for AS, linkage at
the major histocompatibility complex region (chromo-
some 6p21) was evident, exhibiting the highest multi-
point LOD score (4.96 at marker HLA–B). Strong
linkage was seen at a region on chromosome 9p21–9p24,
with a LOD score of 3.72 at marker D9S157. When
compared with a companion cohort of AS families, the
linkage at this region was found in association with AAU
but not with AS. A third region on chromosome 1q23–
1q31 was observed to have suggestive linkage (LOD 2.05
at marker D1S238), which overlaps with a region asso-
ciated with AS.
Conclusion. This is the first study in which a
genetic region for AAU has been identified by genome-
wide scan. Even though AS was highly prevalent in this
cohort of families, a locus at chromosome 9p21–9p24
was identified that uniquely associates with AAU. Iden-
tifying the genetic perturbation at this region may
advance our understanding of the mechanisms involved
in tissue-specific pathology of complex inflammatory
diseases.
Supported by unrestricted funds from Research to Prevent
Blindness to the Casey Eye Institute. Dr. Martin’s work was supported
by the Research to Prevent Blindness Career Development Award and
National Eye Institute grant EY-13139. Dr. Smith’s work was sup-
ported by the Research to Prevent Blindness Career Development
Award. Dr. Rosenbaum’s work was supported by a Research to
Prevent Blindness Senior Scholar Award. Dr. Reveille’s work was
supported by NIH grant R01-AR-46208 from the National Institute of
Arthritis and Musculoskeletal and Skin Diseases.
1
Tammy M. Martin, PhD, Trudy M. Doyle, BS, Barbara M.
Rajska, BS, Jessica E. Coffman, BS, Justine R. Smith, MD, James T.
Rosenbaum, MD: Oregon Health & Science University, Portland;
2
Ge
Zhang, MCM, Jingchun Luo, MCM, Li Jin, MD: Center for Genome
Information, University of Cincinnati, Cincinnati, Ohio;
3
Matthias D.
Becker, MD, Friederike Mackensen, MD: Interdisciplinary Uveitis
Center, University of Heidelberg, Heidelberg, Germany;
4
Muhammad
A. Khan, MD: Case Western Reserve University, Cleveland, Ohio;
5
Ralph D. Levinson, MD: Jules Stein Eye Institute, University of
California, Los Angeles;
6
H. Ralph Schumacher, MD, University of
Pennsylvania, Philadelphia;
7
N. Kevin Wade, MD: Kerrisdale Profes-
sional Center, Vancouver, British Columbia, Canada;
8
John D. Rev-
eille, MD (representing the North American Spondylitis Consortium):
The University of Texas Health Science Center at Houston.
Drs. Rosenbaum and Reveille contributed equally to this
work.
Address correspondence and reprint requests to Tammy M.
Martin, PhD, Casey Eye Institute, CE-RES, Oregon Health & Science
University, 3375 SW Terwilliger Boulevard, Portland, OR 97239.
E-mail: martint@ohsu.edu.
Submitted for publication March 3, 2004; accepted in revised
form October 8, 2004.
269
Susceptibility loci for complex, immunologically
mediated diseases such as rheumatoid arthritis, systemic
lupus erythematosus, and Crohn’s disease are being
increasingly identified. Ankylosing spondylitis (AS) is a
complex disease characterized by chronic inflammation
of the spine and sacroiliac joints. Disease progresses
from bone and joint erosions to ankylosis, which can
result in a characteristic bent-over posture in some
patients with advanced disease. In addition to sacroiliitis,
inflammation may also be present in peripheral joints
and in extraarticular sites such as the uvea, aorta, or
bowel. AS has a strong genetic component and is
associated with HLA–B27 in ⬎90% of patients of Eu-
ropean descent (1–3). However, the relative genetic
contribution from the major histocompatibility complex
(MHC) has been estimated at 31–45% (4,5). Genome-
wide screens for AS susceptibility loci have been con-
ducted, and several candidate regions in addition to the
MHC have been identified (4,6). These include genomic
regions at 1p, 2p, 2q, 3p, 9q, 10q, 11p, 16q, and 19q.
These studies have not presented genetic data stratified
for any extraarticular manifestations of AS.
Uveitis, or inflammation of the uvea, is a signif-
icant cause of visual loss (7). Clinically, uveitis can be
categorized into distinct phenotypes. Acute anterior
uveitis (AAU; also referred to as acute iritis or acute
iridocyclitis), which presents unilaterally with sudden
onset, is self-limiting and recurrent and represents the
specific uveitis phenotype associated with AS (8). An
episode of AAU will affect 20–44% of patients with AS,
but AAU also may occur in the absence of systemic
inflammatory disease (5,6,9,10). Although the frequency
of patients with AAU who are positive for HLA–B27
varies among different published surveys (11,12), it is
generally estimated that among Caucasian patients with
AAU, 50% are positive for HLA–B27.
Because AAU does show familial aggregation
(13), we hypothesized that specific genetic factors may
predispose individuals to the development of AAU. To
test this hypothesis, a genome-wide scan was conducted
on families in which multiple members have AAU.
Here, we describe that analysis, which identified a
uveitis-specific genomic region on chromosome 9p.
Therefore, chromosome 9p is likely to harbor a gene
involved in AS, and this gene particularly influences the
risk of uveitis.
PATIENTS AND METHODS
Family recruitment. Families having 2 or more mem-
bers with either AAU or AS were recruited by investigators at
the Casey Eye Institute (Portland, OR) or by investigators
representing the North American Spondylitis Consortium
(NASC) (under the direction of JDR). Both studies were
approved by their respective institutional review boards, and
all participants provided informed consent.
The clinical criteria for the diagnosis of AAU include
documented evidence of anterior chamber inflammation, as-
sessed by slit lamp biomicroscopic examination, that is sudden
in onset, unilateral, and resolves within 12 weeks. This form of
uveitis is typically episodic, and although it presents unilater-
ally, it may flip-flop, involving the companion eye in recur-
rence. Individuals were considered to be affected with uveitis if
1) they met the AAU criteria after careful review of ophthal-
mology chart notes (as assessed by JRS) or 2) affirmation of
the diagnosis of uveitis was present in a medical chart (usually
a rheumatologist’s record) and the diagnosis was self-reported
by the patient. For the NASC study, family members were
considered to have AS only if they met the modified 1984 New
York criteria for AS (14) and had radiographs available for
review. The radiographs were reevaluated according to the
protocol established by the NASC to verify the diagnosis of AS,
which entailed the radiographs being read by 3 different
reviewers: a radiologist, a rheumatologist (JDR), and the
referring NASC study rheumatologist; discrepancies were re-
solved by a fourth rheumatologist reviewer, who read the
radiographs in a blinded manner. In the few instances in which
radiographs were not available (⬍10% of patients), the diag-
nosis was made by either magnetic resonance imaging or
computed tomography scans or by radiologist reports using
wording consistent with grade II, III, or IV sacroiliitis as
required by the modified New York criteria (14).
Genotyping. Genomic DNA was extracted from peri-
pheral blood samples, which were obtained from each partic-
ipating family member by standard techniques. HLA–B typing
was performed by single-stranded conformational polymor-
phism analysis using commercially available kits (Dynal, Lake
Success, NY). Identification of HLA–DRB1, DQA1, DQB1,
and DPB1 alleles was carried out with high-resolution typing
performed by standard oligotyping techniques using primers
and probes recommended at the Thirteenth International
Histocompatibility Workshop (Victoria, British Columbia,
Canada; May 2002). All 400 markers in ABI PRISM linkage
map MD-10 (Applied Biosystems, Foster City, CA) were
amplified and typed using multiplex polymerase chain reaction
in 5-
l reaction volumes. The reaction products were analyzed
on ABI 3100 automated sequencers, and allele-calling was
conducted using GeneMap software, version 3.0 (Applied
Biosystems). Eighteen markers on chromosome X were ana-
lyzed by pedigree data file xghp (part of GeneHunter Plus).
The observations for chromosome X were neither significant
nor interesting and therefore were not included in the results
presented. The efficiency of typing was 93.8%. Specified
relationships were checked using the Relative program (15).
Genotyping errors and Mendelian inconsistencies were iden-
tified using PedCheck software (16). Pedigrees with apparent
nonpaternity and inconsistent genotypes were not analyzed
further. The genotyping error rate for the combined AAU and
NASC cohort was ⬍1%.
Linkage and linkage disequilibrium analyses. Two-
point and multipoint nonparametric linkage (NPL) analyses
were conducted using the NPL-all (nonparametric linkage
270 MARTIN ET AL
score using all affected relatives) statistic implemented in
GeneHunter Plus (17). One-parameter allele-sharing model
logarithm of odds (ASM LOD) scores were calculated based
on the distribution of test statistics under the null hypothesis
and conditional on the data, using the ASM computer program
(17). The transmission disequilibrium test (TDT) (18) and
pedigree disequilibrium test (PDT) (19) were performed and
implemented using UNPHASED software (20).
RESULTS
Fifty-seven families representing 76 affected sib-
pairs were included in this analysis (Table 1). Among the
76 affected sibpairs analyzed, 6 had no history of AS in
either sibling, 12 sibpairs were discordant for AS (al-
though concordant for uveitis), and in the majority (58
sibpairs), both siblings were also diagnosed as having AS.
The 2-point linkage analysis revealed several
markers with a Pvalue less than 0.05 for susceptibility to
AAU (Table 2). For most of these markers, there was
agreement with the TDT, which was performed on those
families for which DNA from both parents of individuals
with AAU was available (Table 2). Even though the
TDT is not a valid test for association when analyzing
multicase families (21), it is still a valid test for linkage.
However, in order to confirm the implicated association,
we also included the PDT results in Table 2 (the PDT is
a valid test for both linkage and association in general
pedigrees).
Results of the multipoint analysis are shown in
Figure 1, which compares genome-wide scans for AAU
and AS (5). Candidate region selections were based on
multipoint linkage analysis in which the Pvalue was ⬍0.05
(data not shown) and are represented graphically in Figure
1 as ASM LOD scores. As can be seen in Figure 1, the
highest LOD scores were achieved on chromosome 6. This
represents a large 46.6-cM region encompassing the MHC
at position 6p21 (peak multipoint ASM LOD 4.96 at
HLA–B). This finding was similar to that observed for AS
and most likely reflects the strong association of AAU and
AS with HLA–B27. Interestingly, the genome-wide scan
for AS revealed a second region on chromosome 6 with
a suggestive LOD score that was not observed in the
AAU analysis (Figure 1).
Table 1. Composition of families studied*
Category
No. of
families
No. of
ASPs
Family with 1 affected sibpair (2 affected siblings) 51 51
Family with 3 affected sibpairs (3 affected siblings) 5 15
Family with 10 affected sibpairs (5 affected siblings) 1 10
Total 57 76
* ASP ⫽affected sibling pair.
Table 2. Two-point linkage and TDT and PDT analyses of chromosomal markers and acute anterior uveitis susceptibility*
Chromosome Marker
Position,
cM NPL
ASM
LOD
P, 2-point
analysis
P, TDT
analysis
P, PDT
analysis
1q23 D1S2878 177.86 0.9422 1.6473 0.0268 0.0896 0.0833
1q25 D1S238 202.73 0.9132 2.5418 0.0307 0.0143 0.0142
1q25 D1S2877 205.40 0.9638 2.6669 0.0242 0.0956 0.2676
3p24 D3S1266 52.60 0.9249 1.3209 0.0291 0.0077 0.0317
3q24 D3S1569 158.38 0.8050 1.0014 0.0495 0.0090 0.0109
3q28 D3S1262 201.14 0.8480 1.1832 0.0411 0.0455 0.0053
5q14 D5S428 95.40 0.8659 1.2343 0.0380 0.0009 0.0833
5q15 D5S644 104.76 0.8371 1.0699 0.0431 0.0008 0.0229
6p22 D6S422 35.66 1.1337 3.1658 0.0110 0.0593 0.1164
6p22 (MHC) D6S276 40.69 0.8915 2.0775 0.0356 0.0522 0.0445
6p21 (MHC) HLA-B 44.80 1.1775 3.4957 0.0087 ⬍0.0001 ⬍0.0001
6p21 (MHC) DRB 45.90 1.6999 5.0109 0.0003 0.0143 0.0143
6p21 (MHC) DQA 45.98 1.2217 2.5920 0.0068 0.0348 0.0116
6p21 (MHC) DQB 46.05 1.5404 5.1134 0.0009 0.0143 0.0038
6p21 (MHC) DPB 46.65 0.9717 2.3482 0.0247 0.0455 0.1140
6p21 (MHC) D6S1610 53.81 1.0478 1.5986 0.0171 0.0833 0.1503
9p24 D9S288 9.83 1.0774 1.2693 0.0137 0.0027 0.0234
9p23 D9S286 18.06 0.8745 0.9470 0.0366 0.0956 0.0254
9p22 D9S285 29.52 0.8732 1.1063 0.0368 0.3173 0.2596
9p22 D9S157 32.24 0.8849 1.6027 0.0349 0.0253 0.0455
9q22 D9S283 94.85 0.8462 1.5798 0.0415 0.0290 0.0833
10q23 D10S1686 105.04 0.9148 1.2194 0.0308 0.0047 0.0176
16p13 D16S3103 32.07 0.8371 1.3622 0.0431 0.2207 0.1025
* Only those chromosomal markers with a 2-point analysis Pvalue ⬍0.05 are shown. TDT ⫽transmission disequilibrium test; PDT ⫽pedigree
disequilibrium test; NPL ⫽nonparametric linkage; ASM LOD ⫽allele-sharing model logarithm of odds; MHC ⫽major histocompatibility complex.
UNIQUE GENETIC REGION IN AAU 271
Another region showing evidence for AAU was
found on chromosome 9p. This region did not show any
linkage to AS (Figure 1). Using multipoint linkage
analysis, the strongest ASM LOD score was 3.72 at
marker D9S157 for a region spanning 43.5 cM (9p21–
9p24). Significance within this region was observed by
TDT and PDT as well as by linkage analysis (Table 2).
A third region on chromosome 1q exhibited
suggestive linkage with AAU by linkage analysis and
TDT (Figure 1 and Table 2). This large 45.5-cM area at
1q23–1q31 (from 166.9 to 212.4 cM, maximum ASM
LOD 2.05 at marker D1S238) overlaps with a region
identified by the NASC for AS (5).
In this analysis, several other regions showed
putative linkage to AAU, including regions at 3p24,
3q24, 3q28, 5q14, 5q34, 9q22, 10q23, 13q14, 15q11–
15q13, and 16p12. Some of these areas showed overlap
with the AS companion scan (3q28, 10q23, and 16p12).
However, several regions that were identified for AAU
were not identified by the AS scan (3p24, 3q24, 5q14,
5q34, 9q22, 13q14, and 15q11–15q13).
According to the criteria described by Lander
and Kruglyak, significant and suggestive linkage are
represented by LOD scores ⬎3.3 and ⬎1.9, respectively
(22). Therefore, based on our data, we have evidence
that the MHC is significantly linked with AAU in both
2-point and multipoint analyses. In addition, the 9p21–
9p24 linkage with AAU was significant by multipoint
analysis (ASM LOD 3.72), and the signal at 1q23–1q31
was suggestive (ASM LOD 2.05).
DISCUSSION
This report is the first to describe results of a
genome-wide scan of AAU, a disease that represents an
extraarticular manifestation of AS. Several chromo-
somal regions linked with AS were found to also be in
linkage with AAU, most significantly the MHC (on
chromosome 6p21) and a region on chromosome 1q23–
1q31. Importantly, several regions that were linked only
with AAU and not AS were identified, and one such
region was found to be highly significantly linked. This
area at 9p21–9p24 had a maximum LOD score of 3.72
(by multipoint analysis) and was also evident by TDT
analysis (P⫽0.025).
The candidate regions reported here overlap with
those observed in previous studies of AS susceptibility
(6). Because our cohort of families with uveitis is largely
a subset of families with AS, it is difficult (if not
impossible) to distinguish an “AS” locus from an
“AAU” locus. Laval et al (6) did detect “suggestive”
linkage at marker D9S288, which was also found in
region 9p in our study. However, the linkage of chromo-
some 9p was not observed in the companion NASC scan
(5). Therefore, it is highly suggestive that this region is
linked with uveitis.
The region of chromosome 9p identified here is
relatively large and contains at least 100 genes. However,
several potential candidate genes reside in this area,
including transcription factors/regulators known to influ-
ence immune responses, signaling molecules with kinase
Figure 1. Comparison of genome-wide scans for acute anterior uveitis (AAU) and ankylosing spondylitis (AS), showing unique regions related to
uveitis. Results shown are allele-sharing model (ASM)–derived multipoint logarithm of odds (LOD) scores against genome position (cM). Solid dark
blue line represents data for AAU, and dashed brown line represents data for AS. Vertical pink lines represent boundaries for each chromosome,
and the chromosome numbers are shown across the top of the graph. For AAU, 76 affected sibpairs were analyzed. The AS data represent 244
affected sibpairs (5).
272 MARTIN ET AL
activity, and the genes encoding the type I interferon
(IFN) family. The type I IFN molecules are potent
cytokines that mediate host defense and immune system
homeostasis. Another interesting gene that resides
within this locus is RFX3, a transcription regulator that
belongs to a family referred to as regulatory for X box
(RFX). Other members of this family participate in
activation of class II MHC genes (RFX5) and in modu-
lation of interleukin-5 receptor
␣
(RFX1), which is
important for B cell activation (23,24). Fine-mapping
studies are under way to further refine this broad region.
Many rheumatic diseases such as systemic lupus
erythematosus, rheumatoid arthritis, Sjo¨gren’s syn-
drome, Wegener’s granulomatosis, and Behc¸et’s disease
involve multiple organ systems. It is critical to ask why
renal disease develops in one patient with lupus, while
another patient will have primarily joint involvement.
Why does vasculitis complicate the course in a minority
of patients with rheumatoid arthritis? Regarding spon-
dylarthritis, extraarticular manifestations such as pso-
riasis and inflammatory bowel disease also occur in ad-
dition to AAU. All of these distinct sites of local
inflammation presumably are associated with specific ge-
netic risks, and certain genetic factors that contribute to a
subset of these disease manifestations will likely be deter-
mined. The CARD15 gene shows strong linkage to Crohn’s
disease but not to ulcerative colitis (25,26). Given that
inflammatory bowel disease is part of the spectrum of
spondylarthritis, the role of CARD15 mutations in AS has
been examined. With the exception of a possible associa-
tion with disease severity, no evidence that CARD15 has a
genetic influence on AS has been found (27–32).
The results of our study suggest that a genetic
factor contributes to a specific manifestation, acute
anterior uveitis, that is strongly associated with spondyl-
arthritis. In this preliminary study, the relatively small
sample size (i.e., 76 affected sibpairs) limits the power of
our analysis. Even though the result on chromosome 9p
was striking, a larger cohort will be necessary to confirm
our findings. Identification of the specific gene and
elucidation of the function of the gene product respon-
sible for this susceptibility should contribute greatly to
understanding the pathogenesis of uveitis.
ACKNOWLEDGMENTS
The authors gratefully acknowledge the Spondylitis
Association of America (Sherman Oaks, CA), and are espe-
cially grateful for the efforts of Michael H. Weisman, MD, and
David T. Y. Yu, MD, who contributed so much to the family
collections.
REFERENCES
1. Caffrey MF, James DC. Human lymphocyte antigen association in
ankylosing spondylitis [letter]. Nature 1973;242:121.
2. Schlosstein LP, Terasaki PI, Bluestone R, Pearson CM. High
association of an HLA antigen, W27, with ankylosing spondylitis.
N Engl J Med 1973;288:704–6.
3. Brewerton DA, Hart FD, Nicholls A, Caffrey M, James DC,
Sturrock RD. Ankylosing spondylitis and HL-A 27. Lancet 1973;
1:904–7.
4. Brown MA, Pile KD, Kennedy LG, Campbell D, Andrew L,
March R, et al. A genome-wide screen for susceptibility loci in
ankylosing spondylitis. Arthritis Rheum 1998;41:588–95.
5. Zhang G, Luo J, Bruckel J, Weisman M, Schumacher HR, Khan
MA, et al. Genetic studies in familial ankylosing spondylitis
susceptibility. Arthritis Rheum 2004;50:2246–54.
6. Laval SH, Timms A, Edwards S, Bradbury L, Brophy S, Milicic A,
et al. Whole-genome screening in ankylosing spondylitis: evidence
of non-MHC genetic-susceptibility loci. Am J Hum Genet 2001;
68:918–26.
7. Nussenblatt RB. The natural history of uveitis. Int Ophthalmol
1990;14:303–8.
8. Rosenbaum JT. Characterization of uveitis associated with spon-
dyloarthritis. J Rheumatol 1989;16:792–6.
9. Rosenbaum JT. Acute anterior uveitis and spondyloarthropathies.
Rheum Dis Clin North Am 1992;18:143–51.
10. Gran JT, Skomsvoll JF. The outcome of ankylosing spondylitis: a
study of 100 patients. Br J Rheumatol 1997;36:766–71.
11. Wakefield D, Montanaro A, McCluskey P. Acute anterior uveitis
and HLA-B27. Surv Ophthalmol 1991;36:223–32.
12. Brewerton DA, Caffrey M, Nicholls A, Walters D, James DC.
Acute anterior uveitis and HL-A 27. Lancet 1973;2:994–6.
13. Said-Nahal R, Miceli-Richard C, Berthelot JM, Duche´ A, Dernis-
Labous E, Le Ble´vec G, et al, for Groupe Franc¸ais d’Etude
Ge´ne´tique des Spondylarthropathies. The familial form of spon-
dylarthropathy: a clinical study of 115 multiplex families. Arthritis
Rheum 2000;43:1356–65.
14. Van der Linden S, Valkenburg HA, Cats A. Evaluation of
diagnostic criteria for ankylosing spondylitis: a proposal for mod-
ification of the New York criteria. Arthritis Rheum 1984;27:361–8.
15. Goring HH, Ott J. Relationship estimation in affected sib pair
analysis of late-onset diseases. Eur J Hum Genet 1997;5:69–77.
16. O’Connell JR, Weeks DE. PedCheck: a program for identification
of genotype incompatibilities in linkage analysis. Am J Hum Genet
1998;63:259–66.
17. Kong A, Cox NJ. Allele-sharing models: LOD scores and accurate
linkage tests. Am J Hum Genet 1997;61:1179–88.
18. Spielman RS, McGinnis RE, Ewens WJ. Transmission test for
linkage disequilibrium: the insulin gene region and insulin-depen-
dent diabetes mellitus (IDDM). Am J Hum Genet 1993;52:
506–16.
19. Martin ER, Monks SA, Warren LL, Kaplan NL. A test for linkage
and association in general pedigrees: the pedigree disequilibrium
test. Am J Hum Genet 2000;67:146–54.
20. Dudbridge F. Pedigree disequilibrium tests for multilocus haplo-
types. Genet Epidemiol 2003;25:115–21.
21. Ewens WJ, Spielman RS. The transmission/disequilibrium test:
history, subdivision, and admixture. Am J Hum Genet 1995;57:
455–64.
22. Lander E, Kruglyak L. Genetic dissection of complex traits:
guidelines for interpreting and reporting linkage results. Nat
Genet 1995;11:241–7.
23. Masternak K, Reith W. Promoter-specific functions of CIITA and
the MHC class II enhanceosome in transcriptional activation.
EMBO J 2002;21:1379–88.
24. Iwama A, Pan J, Zhang P, Reith W, Mach B, Tenen DG, et al.
Dimeric RFX proteins contribute to the activity and lineage
UNIQUE GENETIC REGION IN AAU 273
specificity of the interleukin-5 receptor
␣
promoter through
activation and repression domains. Mol Cell Biol 1999;19:3940–50.
25. Hugot J-P, Chamaillard M, Zouali H, Lesage S, Cezard J, Belaiche
J, et al. Association of NOD2 leucine-rich repeat variants with
susceptibility to Crohn’s disease. Nature 2001;411:599– 603.
26. Ogura Y, Bonen D, Inohara N, Nicolae D, Chen F, Ramos R, et
al. A frameshift mutation in NOD2 associated with susceptibility
to Crohn’s disease. Nature 2001;411:603–6.
27. Brown MA, Brophy S, Bradbury L, Hamersma J, Timms A, Laval
S, et al. Identification of major loci controlling clinical manifesta-
tions of ankylosing spondylitis. Arthritis Rheum 2003;48:2234–9.
28. Crane AM, Bradbury L, van Heel DA, McGovern DP, Brophy S,
Rubin L, et al. Role of NOD2 variants in spondylarthritis. Arthritis
Rheum 2002;46:1629–33.
29. D’Amato M. The Crohn’s associated NOD2 3020InsC frameshift
mutation does not confer susceptibility to ankylosing spondylitis.
J Rheumatol 2002;29:2470–1.
30. Ferreiros-Vidal I, Amarelo J, Barros F, Carracedo A, Gomez-
Reino JJ, Gonzalez A. Lack of association of ankylosing spondy-
litis with the most common NOD2 susceptibility alleles to Crohn’s
disease. J Rheumatol 2003;30:102–4.
31. Miceli-Richard C, Zouali H, Lesage S, Thomas G, Hugot JP,
Said-Nahal R, et al. CARD15/NOD2 analyses in spondylarthro-
pathy. Arthritis Rheum 2002;46:1405–6.
32. Van der Paardt M, Crusius JB, de Koning MH, Murillo LS, van
de Stadt RJ, Dijkmans BA, et al. CARD15 gene mutations are
not associated with ankylosing spondylitis. Genes Immun 2003;
4:77–8.
274 MARTIN ET AL
