Mutagenesis vol. 27 no. 2 pp. 153–159, 2012
doi:10.1093/mutage/ger047
Seeking genetic susceptibility variants for colorectal cancer: the EPICOLON
consortium experience
Sergi Castellvı́-Bel1,*, Clara Ruiz-Ponte2, Ceres
Fernández-Rozadilla2, Anna Abulı́1,3, Jenifer Muñoz1,
Xavier Bessa3, Alejandro Brea-Fernández2, Marta Ferro2,
Marı́a Dolores Giráldez1, Rosa M. Xicola4, Xavier Llor4,
Rodrigo Jover5, Josep M. Piqué1, Montserrat Andreu3,
Antoni Castells1 and Angel Carracedo2 for the
Gastrointestinal Oncology Group of the Spanish
Gastroenterological Associationy
1
Department of Gastroenterology, Hospital Clı́nic, CIBERehd, IDIBAPS,
University of Barcelona, Villarroel 170, 08036 Barcelona, Catalonia, Spain,
2
Galician Public Foundation of Genomic Medicine (FPGMX), CIBERER,
Genomics Medicine Group, Hospital Clinico, University of Santiago de
Compostela, Choupana s/n, 15706 Santiago de Compostela, Galicia, Spain,
3
Gastroenterology Department, Parc de Salut Mar, Institut Municipal
d’Investigació Mèdica (IMIM), Pompeu Fabra University, Passeig Marı́tim
25-29, 08003 Barcelona, Catalonia, Spain, 4Section of Digestive Diseases and
Nutrition, University of Illinois at Chicago, 909 S. Wolcott Ave. COMRB
5140, Chicago, IL, 60612, USA and 5Department of Gastroenterology,
Hospital General d’Alacant, Pintor Baeza 12, 03010 Alicante, Spain,
y
All authors are listed under the section Addendum.
*
To whom correspondence should be addressed. Department of Gastroenterology, Hospital Clı́nic, Villarroel 170, 08036 Barcelona, Spain. Tel: þ34 93
2275418; Fax: þ34 93 2279387; Email: [email protected]
Received on May 27, 2011; revised on June 16, 2011;
accepted on June 21, 2011
The EPICOLON consortium was initiated in 1999 by
the Gastrointestinal Oncology Group of the Spanish
Gastroenterology Association. It recruited consecutive,
unselected, population-based colorectal cancer (CRC)
cases and control subjects matched by age and gender
without personal or familial history of cancer all over
Spain with the main goal of gaining knowledge in Lynch
syndrome and familial CRC. This epidemiological, prospective and multicentre study collected extensive clinical
data and biological samples from 2000 CRC cases and
2000 controls in Phases 1 and 2 involving 25 and 14
participating hospitals, respectively. Genetic susceptibility
projects in EPICOLON have included candidate-gene
approaches evaluating single-nucleotide polymorphisms/
genes from the historical category (linked to CRC risk by
previous studies), from human syntenic CRC susceptibility
regions identified in mouse, from the CRC carcinogenesisrelated pathways Wnt and BMP, from regions 9q22 and
3q22 with positive linkage in CRC families, and from the
mucin gene family. This consortium has also participated
actively in the identification 5 of the 16 common, lowpenetrance CRC genetic variants identified so far by
genome-wide association studies. Finishing their own
pangenomic study and performing whole-exome sequencing in selected CRC samples are among EPICOLON
future research prospects.
Preface
Colorectal cancer (CRC) continues to be a major public health
problem, although it is a preventable and potentially curable
neoplasm. CRC is the second most common cancer in Western
countries and it also represents the second leading cause of
cancer-related death among men and women. In the USA, there
were 102 900 estimated new CRC cases diagnosed during
2010 and 51 370 deaths related to this cancer in the same year
(26 580 males and 24 790 women) (1). Risk of developing this
neoplasm in the general population is around 5–6% at the age
of 70, and it rises exponentially with age.
Genetic factors involved in CRC susceptibility
Familial aggregation is defined as occurrence of CRC in more
members of a family than can be readily accounted for by chance
(2). Familial clustering may be caused by sharing either genetic
predisposition or environmental factors. Regarding CRC, these
environmental effects may be particularly relevant because
families share dietary customs and recreational habits. Obesity,
sedentary life, cigarette smoking or a diet rich in fat and red meat
are among the high-risk environmental factors most commonly
considered for CRC and monitoring them is important in terms of
prevention strategies (3). On the other hand, epidemiological
studies have also assessed the contribution of shared environment
in cancers using twin studies to measure if concordance for
cancer is higher among monozygotic twins who have a common
genetic background than among dizygotic twins who, on average,
share half of their segregating genes. A survey performed in
Scandinavian population concluded that inherited genetic factors
seem to make a minor contribution to susceptibility in most types
of cancers, indicating that environment has the primary responsibility. However, this study also detected a relatively higher
effect of heritability in prostate and CRC (4). A more recent
study in a similar population explored the extension of the risk
for CRC due to heritable genetic or environmental factors. It
included all first-degree relatives (parents, siblings and children)
and spouses, concluding that genetic effects are likely to be more
important for CRC than environment (5).
Familial adenomatous polyposis and Lynch syndrome are the
more frequent hereditary CRC syndromes and they are caused
by germ line mutations in APC, MUTYH and mismatch repair
(MMR) genes MLH1, MSH2, MSH6 and PMS2, respectively
(2). These hereditary Mendelian syndromes show earlier onset
and stronger familial aggregation than familial non-syndromic
CRC. However, they only correspond to a minority of the total
CRC burden (5%). The genetic components involved in these
less frequent hereditary forms were successfully identified in the
past two decades and they correspond to rare highly penetrant
alleles that predispose to CRC. Excluding these hereditary
syndromes, most CRC cases do not have a positive family
history and they are considered sporadic, although there is some
Ó The Author 2012. Published by Oxford University Press on behalf of the UK Environmental Mutagen Society.
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S. Castellvı́-Bel et al.
familial aggregation in an important percentage corresponding
to the familial CRC category (30% of total CRC cases) (6).
Genetic variants predisposing to familial CRC are mainly not
identified, and, therefore, most heritability factors involved in
CRC still remain unrevealed. Among CRC cases with an
unknown germ line genetic basis, CRC cases with a strong
familial aggregation without MMR involvement, also known as
familial CRC type X (7), are particularly interesting. In these
CRC families, strict clinical Amsterdam I criteria are met: (i) at
least three CRC cases with histological confirmation (one firstdegree relative of the other three), excluding familial adenomatous polyposis; (ii) at least two successive generations affected
and (iii) one of the relatives is affected with CRC before age 50.
Recently, new common low-penetrance genetic variants for
CRC have been identified by case–control genome-wide
association studies (GWAS) permitting to point out so far 14
loci for CRC genetic susceptibility in chromosomal regions
8q23.3, 8q24.21, 10p14, 11q23.11, 14q22.2, 15q13.3, 16q22.1,
18q21.1, 19q13, 20p12.3, 1q41, 3q26.2, 12q13.3 and 20q13.33
(8,9). Additionally, genetic linkage efforts in families with
several members affected with familial CRC have allowed also
pinpointing other candidate chromosomal regions for CRC
genetic susceptibility. Among them, the more solid runners-up
are 9q22 (10–13) and 3q21–q24 (14–17). Moreover, there is
also very preliminary evidence of the implication of new genes
in familial CRC. Examples could be the GALNT12 gene in
region 9q22, highly expressed in the digestive system and
involved in glycosilation of proteins such as mucins (18) or the
BMP4 and PTPRJ genes (19,20).
Fig. 1. Spanish hospitals that participated in the EPICOLON consortium.
154
The EPICOLON consortium: an initiative to characterise
lynch syndrome and familial CRC in spain
EPICOLON was initiated in 1999 by the Gastrointestinal
Oncology Group of the Spanish Gastroenterology Association
(Asociación Española de Gastroenterologı́a) as a cooperative
project to recruit in Spain consecutive, unselected populationbased CRC cases and matched controls by age and gender
without personal or familial history of cancer in order to gain
knowledge in Lynch syndrome and familial CRC. This
epidemiological, prospective and multicentric study collected
extensive clinical data and biological samples from 2000
CRC cases and 2000 controls in two independent phases. Phase
1 started in November 2000 and closed up in October 2001 in
25 participating hospitals (Figure 1; Addendum). Later on,
Phase 2 extended from 2006 to 2008 in 14 participating Spanish
hospitals (Addendum). Among the involved centers, this
consortium is now headed by the Gastroenterology departments
of Hospital Clinic and Hospital del Mar in Barcelona, Hospital
Germans Trias i Pujol in Badalona and Hospital General in
Alicante, as well as by the Genomics Medicine Group of the
Galician Public Foundation of Genomic Medicine (FPGMX) in
Santiago de Compostela.
Demographic, clinical and tumour-related characteristics, as
well as a detailed family history, were obtained from CRC
cases using a pre-established questionnaire. Personal parameters at baseline included place and date of birth, gender,
personal history of neoplasia (LS-related tumours and colorectal
adenomas), age at CRC diagnosis and presence of synchronous
colorectal neoplasms. Tumour-related parameters included
location, histology, TNM stage and degree of differentiation.
CRC genetic susceptibility in the EPICOLON consortium
Synchronous lesions were assessed by colonoscopy before or
immediately after surgery, as well as through systematic review
of the resected specimen. Pedigrees were traced backward and
laterally as far as possible, and at least out to second-degree
relatives, with regard to cancer history. Age at cancer
diagnosis, type and location were registered for each affected
family member. Demographic, clinical and tumour-related
characteristics of CRC patients included are shown in Table I.
Exclusion criteria for CRC cases in EPICOLON were familial
adenomatous polyposis and personal history of inflammatory
bowel disease. This study was approved by the institutional
ethics committee of each participating hospital and written
informed consent was obtained from all patients.
Efforts made by all EPICOLON participating centres permitted
to collect extensive clinical data and biological samples from
2000 CRC cases and 2000 controls and to perform during
the past decade several studies ascertaining epidemiological,
diagnostic and molecular aspects on Lynch syndrome and familial CRC. A first study established a 2.5% frequency for
clinical diagnosis of Lynch syndrome in Spain according to the
Amsterdam II criteria (21). Subsequent studies focused on the
clinical characterisation of this cohort concerning synchronous
Table I. Demographic, clinical and familial characteristics of CRC patients included in EPICOLONa
Characteristics
Age
Mean age (SD), years
Age at diagnosis, n (%)
,50
.50
Gender, n (%)
Male
Female
Site of tumour, n (%)
Colon
Rectum
Missing data
TNM tumour stageb, n (%)
I
II
III
IV
Could not be assessed
Degree of differentiation, n (%)
Well or moderate
Poor
Could not be assessed
Previous or synchronous CRC, n (%)
No
Yes
Missing data
Previous or synchronous colorectal adenoma, n (%)
No
Yes
Missing data
Previous LS-associated cancerc, n (%)
No
Yes
Missing data
First-degree relative with CRC, n (%)
No
Yes
Missing data
First-degree relative with CRC ,50 years, n (%)
No
Yes
Missing data
First-degree relative with LSc-associated cancer, n (%)
No
Yes
Missing data
First-degree relative with LSc-associated cancer ,50
years, n (%)
No
Yes
Missing data
Epicolon I (N 5 1096)
Epicolon II (N 5 895)
70.2 (11.3)
70.9 (10.7)
50 (4.6)
1046 (95.5)
42 (4.7)
853 (95.3)
649 (59.3)
447 (40.7
565 (63.1)
330 (36.9)
707 (64.6)
388 (35.4)
1
592 (67.3)
287 (32.7)
16
127
451
294
182
139
292
278
130
(12.0)
(42.8)
(27.9)
(17.3)
42
(16.6)
(34.8)
(33.1)
(15.5)
56
911 (93.1)
68 (6.9)
117
731 (90.2)
79 (9.8)
85
1030 (94.1)
65 (5.9)
1
844 (95.2)
43 (4.8)
8
806 (73.6)
289 (26.4)
1
582 (65.6)
305 (34.4)
8
1068 (97.5)
27 (2.5)
1
887 (99.1)
8 (0.9)
0
949 (86.7)
146 (13.3)
1
765 (85.5)
130 (14.5)
0
1069 (97.6)
26 (2.4)
1
886 (99.0)
9 (1.0)
0
903 (82.5)
192 (17.5)
1
744 (83.2)
150 (16.8)
1
1044 (95.3)
51 (4.7)
1
867 (97.6)
21 (2.4)
7
LS, Lynch syndrome.
a
Cases without biological sample available or carriers of mutation in the MMR genes or MUTYH are not included.
b
Stage I indicates tumour 1–2 (T1–T2), no regional lymph node metastasis and no metastasis; Stage II, T3–T4, no regional lymph node metastasis and no metastasis;
Stage III, any tumour, Node 1–3 and no metastasis and Stage IV, any tumour, any node and distant metastasis.
c
Other than CRC.
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S. Castellvı́-Bel et al.
CRC (22), MMR-proficient CRC fulfilling Amsterdam criteria
(23) or metachronous CRC (24). More importantly, other studies
focused on the molecular characterisation of CRC patients
regarding MMR identification of MMR mutation carriers (25–
27), MUTYH mutational spectrum (28), COX expression in
MMR-deficient CRC (29), performance of microsatellite marker
panels in MMR-deficient CRC (30), contribution of BRAF
mutational analysis in Lynch syndrome identification (31) or
aberrant methylation in sporadic multiple CRC (32). Finally,
other studies evaluated the performance of clinical guidelines for
Lynch syndrome identification (25,33), MMR mutation prediction tools (34,35) or tumour response to fluorouracil (5-FU)
adjuvant chemotherapy according to the MMR status (36,37).
CRC genetic predisposition projects within EPICOLON
Besides the above-mentioned studies, there have also been
several efforts in EPICOLON to identify or evaluate new lowpenetrance genetic susceptibility variants for CRC. For this
purpose, germ line DNA samples from CRC cases and age- and
gender-matched controls without personal or family history of
cancer were available from this cohort to perform genetic
association case–control studies. Five hundred and fifteen CRC
samples and 515 controls were collected in EPICOLON Phase 1,
corresponding to a selection of samples with sufficient DNA
quality to be genotyped with high-throughput genotyping
techniques. The number of germ line DNA samples available
from CRC cases in Phase 1 was actually higher (1100) and
they were all included in some studies when it was permitted by
the used genotyping approach (i.e. real-time polymerase chain
reaction assays with hydrolysis probes). Regarding EPICOLON
Phase 2, high-quality germ line DNA was available from .900
CRC cases and equal number of matched controls.
Since 2005, several genetic association candidate-gene approaches have been pursued within EPICOLON aiming to
identify genetic susceptibility variants for CRC. Firstly, singlenucleotide polymorphisms (SNPs)/genes were selected to be
studied from the historical category (linked to CRC risk by
previous studies), from human syntenic CRC susceptibility
regions identified in mouse, from the CRC carcinogenesis-related
pathways Wnt and BMP, from regions 9q22 and 3q22 with
positive linkage in CRC families and from the mucin gene family.
A first study evaluated the genetic variation in the ARLTS1 gene
(38) in EPICOLON Phase 1, a tumour suppressor gene of the
ADP-ribosylation factor family with proapoptotic characteristics
identified in chromosome 13q14 and potentially involved in
susceptibility to familial cancer. Variant p.C148R (c.442T.C;
rs3803185) showed for the first time in CRC statistically significant differences between cases and controls [odds ratio (OR)
5 1.45, 95% confidence interval (95% CI) 5 1.13–1.86, P 5
0.003], sporadic cases and controls (OR 5 1.59, 95% CI 5
1.13–2.23, P 5 0.007) and familial cases and controls (OR 5
1.55, 95% CI 5 1.10–2.19, P 5 0.01) in agreement with
a hypothetical moderate increase of the cancer risk linked to the
C148R ARLTS1 variant, both in sporadic and familial CRC cases.
Next candidate-gene approach in EPICOLON analysed the
human-mouse syntenic regions defined by 15 Susceptibility to
CRC (Scc) loci, searching for relevant genes that could be
functionally related to carcinogenetic processes. Selection of
these genes was performed on the basis of enriched expression
in primary affected tissues in humans. Once the 21 candidate
genes were chosen, 147 SNPs within them were genotyped in
515 CRC cases and 515 controls from Phase 1 to find evidence
156
of any new potential association signal. By these means, we
were able to identify a region defined by rs954353, located in
the 5# untranslated region of the CYR61 gene (39). CYR61 was
proposed earlier as a connection point among signaling pathways
and a probable marker for early CRC detection. However,
despite this interesting candidate-gene selection strategy, the
rs954353 association could not be replicated in Phase 2 (933
CRC cases and 955 controls). We believe that the reduced
sample size from our study may have been a key factor in its
unsuccessful replication, and, therefore, larger cohorts may be
needed to fully ascertain the relationship between this
polymorphism and CRC genetic susceptibility.
Another candidate-gene strategy evaluated two main
carcinogenesis-related pathways, Wnt and BMP and their
genetic variation in EPICOLON Phase 2 (40). A total of 45
SNPs located either exonic or regulatory regions, corresponding to 21 genes were evaluated. Unfortunately, none of the
screened SNPs were significantly associated with an altered
risk of CRC, considering ORs and related P values for allelic
and genotypic tests (trend, dominant and recessive).
Very recently, two other candidate-gene approaches have been
concluded. One of them evaluated 10 genetic variants linked to
CRC risk by previous studies (historical category) and 18
selected variants from the mucin gene family in a two-stage
case–control study in EPICOLON Phases 1 and 2. None of the
28 SNPs analysed in this study could be formally associated with
CRC risk. However, variants in ARL11 (rs3803185), ADH1C
(rs698) and GALNTL2 (rs2102302) showed some significance or
were borderline significant in more than one stage (Abulı́ A,
Fernández-Rozadilla C, Alonso-Espinaco V, Muñoz J, Gonzalo
V, Bessa X, González D, Clofent J, Cubiella J, Morillas JD,
Rigau J, Latorre M, Fernández-Bañares F, Peña E, Riestra S,
Payá A, Jover R, Xicola RM, Llor X, Carvajal-Carmona L,
Villanueva CM, Moreno V, Carracedo A, Castells A, Andreu M,
Ruiz-Ponte C, Castellvı́-Bel S, for the Gastrointestinal Oncology
Group of the Spanish Gastroenterological Association, in preparation) and may deserve to be evaluated in additional cohorts.
The other recent candidate-gene strategy genotyped 172 SNPs in
84 genes located within regions 9q22–q31 and 3q21–q24, also
in a two-stage case–control study in EPICOLON Phases 1 and
2. Again, none of the 172 SNPs analysed in this study could be
formally associated with CRC risk. However, rs1444601
(TOPBP1) and rs13088006 (CDV3) in region 3q22 showed
some significance or were borderline significant in more than
one stage and may have an effect on CRC risk (Abulı́ A,
Fernández-Rozadilla C, Giráldez MD, Muñoz J, Gonzalo V,
Bessa X, Bujanda L, Reñé JM, Lanas A, Garcı́a AM, Saló J,
Argüello L, Vilella A, Carreño R, Jover R, Xicola RM, Llor X,
Carvajal-Carmona L, Tomlinson IPM, Kerr DJ, Houlston RS,
Piqué JM, Carracedo A, Castells A, Andreu M, Ruiz-Ponte C,
and Castellvı́-Bel S, for the Gastrointestinal Oncology Group of
the Spanish Gastroenterological Association, manuscript in
preparation).
In addition to candidate-gene approaches, EPICOLON has also
participated in external CRC GWAS by replicating their
statistically significant findings in the EPICOLON cohort. In
such collaborations, this consortium has contributed so far to
the identification of 5 of the 16 common, low-penetrance
CRC genetic variants identified by this methodology [(41,42)
Tomlinson IP, Carvajal-Carmona LG, Dobbins SE, Tenesa A,
Jones AM, Howarth K, Palles C, Broderick P, Jaeger EE,
Farrington S, Lewis A, Prendergast JG, Pittman
AM,
Theodoratou E, Olver B, Walker M, Penegar S, Barclay E,
CRC genetic susceptibility in the EPICOLON consortium
Whiffin N, Martin L, Ballereau S, Lloyd A, Gorman M, Lubbe S;
The COGENT Consortium; The CORGI Collaborators; The
EPICOLON Consortium, Howie B, Marchini J, Ruiz-Ponte C,
Fernandez-Rozadilla C, Castells A, Carracedo A, Castellvi-Bel S,
Duggan D, Conti D, Cazier JB, Campbell H, Sieber O, Lipton L,
Gibbs P, Martin NG, Montgomery GW, Young J, Baird PN,
Gallinger S, Newcomb P, Hopper J, Jenkins MA, Aaltonen LA,
Kerr DJ, Cheadle J, Pharoah P, Casey G, Houlston RS,
Dunlop MG, manuscript in preparation]. Further, there is an
ongoing Spanish GWAS carried out on EPICOLON Phase 2
samples, using an array that allows for simultaneous SNP and
copy-number variants (CNVs) genotyping across the human
genome (Affymetrix Genome-Wide Human SNP Array 6.0). This
study may yield positive results for new SNPs or CNVs involved
in CRC genetic susceptibility. Besides, we are also performing in
EPICOLON an unprecedented GWAS approach on a cohort of
CRC samples that had either been treated with 5-FU/capecitabine
or FOLFOX with the aim to shed a light on the genetic variation
behind the occurrence of adverse drug reactions.
Identification of new common low-penetrance CRC genetic
variants permits to explain part of this neoplasm’s heritability
beyond hereditary syndromes. Therefore, it could be hypothesised
that some of these variants or a combination of them may
correlate with cancer phenotype. To test this possibility, the first
10 GWAS SNPs were evaluated in a genotype–phenotype correlation with several clinical and tumour-related characteristics in
a two-stage case–control study in EPICOLON Phases 1 and 2
(43). Validated results confirmed that the C allele on 8q23.3
(rs16892766) was significantly associated with advanced-stage
tumours (OR, 1.48; 95% CI, 1.15–1.90; P value 5 4.9 103).
The G allele on 8q24.21 (rs6983267) was more common in
patients with a familial history of CRC (OR, 2.02; 95% CI, 1.35–
3.03; P value 5 3.9 104). The combination of rs6983267 on
8q24.21 and rs9929218 on 16q22.2 was associated with a history
of colorectal adenoma (carriers of GG and AA, respectively;
OR, 2.28; 95% CI, 1.32–3.93; P 5 5.0 104). It was
concluded that CRC susceptibility variants at 8q23.3, 8q24.21
and 16q22.2 could be associated differentially with cancer
phenotype and, accordingly, these findings might be used to
develop screening and surveillance strategies. Following
a similar approach, the EPICOLON consortium has also been
involved in the evaluation of the same 10 GWAS SNPs and its
correlation with age, gender and family history in a study
including 42 333 individuals from eight populations (Dunlop
MG, Tenesa A, Farrington SM, Walker M, Theodoratou E,
Prendergast JG, Barnetson RA, Cartwright N, Cetnarskyj R,
Brewster DH, Porteous ME, Kossler T, Pharoah PDP,
Schafmayer C, Bröring D, Schreiber S, Buch S, Hampe J,
Völzke H, Chang-Claude J, Hoffmeister M, Brenner H, von
Holst S, Picelli S, Lindblom A, Swedish Low-Risk Colorectal
Cancer Study Group, Jenkins MA, Hopper JL, Buchanan D,
Young J, Edlund CK, Conti DV, Casey G, Duggan D,
Newcomb P, Abulı́ A, Bessa X, Ruiz-Ponte C, Castellvı́-Bel S,
EPICOLON consortium, Niittymäki I, Tuupanen S, Karhu A,
Aaltonen L, Zanke BW, Greenwood CMT, Rangrej J, Kustra R,
Montpetit A, Hudson TJ, Gallinger S, Barclay E, Martin L,
Gorman M, Carvajal-Carmona L, Spain S, Kemp Z, Howarth K,
Domingo E, Walther A, CORGI Consortium, Cazier JB, Mager R,
Johnstone E, Midgely R, Kerr D, Lubbe S, Broderick P,
Chandler I, Pittman A, Penegar S, COGENT consortium,
Campbell H, Tomlinson I, Houlston RS, manuscript in preparation), and another ongoing study is evaluating these 10 GWAS
SNPs to find out if they have a specific effect in early onset CRC
(Giráldez MD, Bujanda L, Abulı́ A, Fernández-Rozadilla C,
Muñoz J, Gonzalo V, Bessa X, Jover R, Xicola RM, Llor X, Piqué
JM, Carracedo A, Andreu M, Ruiz-Ponte C, Castells A, Balaguer
F, Castellvı́-Bel, for the Gastrointestinal Oncology Group of the
Spanish Gastroenterological Association, manuscript in preparation).
Future prospects
Although there has been a significant increase in the knowledge
of CRC genetic susceptibility in recent years mainly due to
GWAS approaches, there is still a high percentage of unidentified heritability for this cancer. From EPICOLON, we plan to
continue collaborating with groups in the COGENT consortium
(44) in order to identify additional CRC genetic susceptibility
variants. Also, our own GWAS is in its final analysis steps
and may shed new SNPs or CNVs linked to CRC genetic
predisposition.
Very recently, there has been a very significant evolution
regarding technology to search for genes responsible for human
diseases with the advent of next-generation sequencing
techniques (NGS), which have permitted to know the complete
genome of several organisms (45). These new technologies correspond to a variety of strategies based on different
modifications in the DNA template preparation, sequencing
process and genome imaging, as well as in alignment and
assembling methods. Thus, NGS main advantage corresponds
to its ability to generate a huge amount of information at a very
low cost, allowing performing more than just a simple base
sequence analysis. After finishing the human whole-genome
NGS for some individuals, right now several massive cooperative research projects are being performed to sequence a number
of individuals in order to identify structural or nucleotide
variants associated to phenotypic differences (46,47). These
personal genomics endeavours are of particular interest when
they try to elucidate which genomic variation is linked to
a specific disease.
The main application for NGS is human genome resequencing
in order to increase our knowledge of how genetic variation affects
health and disease. Also, it is feasible to direct sequencing only to
genome areas of higher interest with target enrichment techniques
(48). Therefore, the more realistic NGS application nowadays
corresponds to the selected sequencing of the protein coding
genome or exome (whole-exome sequencing) that corresponds to
1% of all human genome (49,50). So far, whole-exome NGS has
not been applied in CRC cases with familial aggregation with an
unknown genetic cause and, accordingly, we are currently
performing it in selected EPICOLON samples.
Addendum
Members of the EPICOLON Consortium (Gastrointestinal
Oncology Group of the Spanish Gastroenterological
Association)
Hospital 12 de Octubre, Madrid: Juan Diego Morillas (local
coordinator), Raquel Muñoz, Marisa Manzano, Francisco Colina,
Jose Dı́az, Carolina Ibarrola, Guadalupe López, Alberto Ibáñez;
Hospital Clı́nic, Barcelona: Antoni Castells (local coordinator),
Virgı́nia Piñol, Sergi Castellvı́-Bel, Francesc Balaguer, Victoria
Gonzalo, Teresa Ocaña, Marı́a Dolores Giráldez, Maria Pellisé,
Anna Serradesanferm, Leticia Moreira, Miriam Cuatrecasas,
Josep M. Piqué; Hospital Clı́nico Universitario, Zaragoza:
Ángel Lanas (local coordinator), Javier Alcedo, Javier Ortego;
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S. Castellvı́-Bel et al.
Hospital Cristal-Piñor, Complexo Hospitalario de Ourense:
Joaquin Cubiella (local coordinator), Ma Soledad Dı́ez,
Mercedes Salgado, Eloy Sánchez, Mariano Vega; Parc de
Salut Mar, Barcelona: Montserrat Andreu (local coordinator),
Anna Abulı́, Xavier Bessa, Mar Iglesias, Agustı́n Seoane,
Felipe Bory, Gemma Navarro, Beatriz Bellosillo; Josep Ma
Dedeu, Cristina Álvarez, Marc Puigvehı́; Hospital San Eloy,
Baracaldo and Hospital Donostia, CIBERehd, University of
Country Basque, San Sebastián: Luis Bujanda (local coordinator) Ángel Cosme, Inés Gil, Mikel Larzabal, Carlos
Placer, Marı́a del Mar Ramı́rez, Elisabeth Hijona, Jose M.
Enrı́quez-Navascués y Jose L. Elosegui; Hospital General
Universitario de Alicante: Artemio Payá (EPICOLON Phase 1
local coordinator), Rodrigo Jover (EPICOLON Phase 2 local
coordinator), Cristina Alenda, Laura Sempere, Nuria Acame,
Estefanı́a Rojas, Lucı́a Pérez-Carbonell; Hospital General de
Granollers: Joaquim Rigau (local coordinator), Ángel Serrano,
Anna Giménez; Hospital General de Vic: Joan Saló (local
coordinator), Eduard Batiste-Alentorn, Josefina Autonell,
Ramon Barniol; Hospital General Universitario de Guadalajara
and Fundación para la Formación e Investigación Sanitarias
Murcia: Ana Marı́a Garcı́a (local coordinator), Fernando
Carballo, Antonio Bienvenido, Eduardo Sanz, Fernando
González, Jaime Sánchez, Akiko Ono; Hospital General
Universitario de Valencia: Mercedes Latorre (local coordinator), Enrique Medina, Jaime Cuquerella, Pilar Canelles, Miguel
Martorell, José Ángel Garcı́a, Francisco Quiles, Elisa Orti;
CHUVI-Hospital Meixoeiro, Vigo: EPICOLON Phase 1: Juan
Clofent (local coordinator), Jaime Seoane, Antoni Tardı́o,
Eugenia Sanchez. EPICOLON Phase 2. Ma Luisa de Castro
(local coordinator), Antoni Tardı́o, Juan Clofent, Vicent
Hernández; Hospital Universitari Germans Trias i Pujol,
Badalona and Section of Digestive Diseases and Nutrition,
University of Illinois at Chicago, IL, USA: Xavier Llor (local
coordinator), Rosa M. Xicola, Marta Piñol, Mercè Rosinach,
Anna Roca, Elisenda Pons, José M. Hernández, Miquel A.
Gassull; Hospital Universitari Mútua de Terrassa: Fernando
Fernández-Bañares (local coordinator), Josep M. Viver,
Antonio Salas, Jorge Espinós, Montserrat Forné, Maria Esteve;
Hospital Universitari Arnau de Vilanova, Lleida: Josep M.
Reñé (local coordinator), Carmen Piñol, Juan Buenestado, Joan
Viñas; Hospital Universitario de Canarias: Enrique Quintero
(local coordinator), David Nicolás, Adolfo Parra, Antonio
Martı́n; Hospital Universitario La Fe, Valencia: Lidia Argüello
(local coordinator), Vicente Pons, Virginia Pertejo, Teresa
Sala; Hospital Sant Pau, Barcelona: Dolors Gonzalez (local
coordinator) Eva Roman, Teresa Ramon, Maria Poca, Ma Mar
Concepción, Marta Martin, Lourdes Pétriz; Hospital Xeral
Cies, Vigo: Daniel Martinez (local coordinator); Fundacion
Publica Galega de Medicina Xenomica (FPGMX), CIBERER,
Genomic Medicine Group-University of Santiago de Compostela, Santiago de Compostela, Galicia, Spain: Ángel Carracedo
(local coordinator), Clara Ruiz-Ponte, Ceres FernándezRozadilla, Ma Magdalena Castro; Hospital Universitario
Central de Asturias: Sabino Riestra (local coordinator), Luis
Rodrigo; Hospital de Galdácano, Vizcaya: Javier Fernández
(local coordinator), Jose Luis Cabriada; Fundación Hospital de
Calahorra (La Rioja) La Rioja: Luis Carreño (local coordinator), Susana Oquiñena, Federico Bolado; Hospital Royo
Villanova, Zaragoza: Elena Peña (local coordinator), José
Manuel Blas, Gloria Ceña, Juan José Sebastián; Hospital
Universitario Reina Sofı́a, Córdoba: Antonio Naranjo (local
coordinator).
158
Funding
The work was carried out (in part) at the Esther Koplowitz
Centre, Barcelona. S.C.-B. and C.F.-R. are supported by
contracts from the Fondo de Investigación Sanitaria (CP 030070 to S.C.-B. and PS09/02368 to C.F.-R.). CIBERehd and
CIBERER are funded by the Instituto de Salud Carlos III.
Fondo de Investigación Sanitaria/FEDER (06/1384, 08/0024,
08/1276, PS09/02368, 10/00918, 11/00219, 11/00681); Instituto de Salud Carlos III (Acción Transversal de Cáncer); Xunta
de Galicia (07PXIB9101209PR); Ministerio de Ciencia e
Innovación (SAF2010-19273); Asociación Española contra el
Cáncer (Fundación Cientı́fica y Junta de Barcelona); Fundació
Olga Torres to S.C.-B. and C.R.-P.; FP7 CHIBCHA Consortium to S.C.-B. and A.C.
Acknowledgements
We are sincerely grateful to all patients participating in this study who were
recruited in 25 (EPICOLON 1) and 14 (EPICOLON 2) Spanish hospitals as
part of the EPICOLON project. We are also grateful to the Spanish National
Genotyping Center (CEGEN-ISCIII)-USC and UPF nodes and the Genome
Analysis Platform of the CIC-BioGUNE:
Conflict of interest statement: None declared.
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