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, a small analysis in Cellular and Molecular Gastroenterology and Hepatology suggests.
Richard Kellermayer, MD, PhD, professor of pediatrics in the Section of Pediatric Gastroenterology, Hepatology and Nutrition at Baylor College of Medicine in Houston, Texas, and colleagues compared the genetic makeup of patients based on their Crohn’s disease location — predominantly in the small bowel (L4) or predominantly in the colon (L2 and/or L3). They then generated bipartite networks of susceptibility genes to study the polygenic background of the disease subtypes. They hypothesize that such networks may govern where a patient develops Crohn’s disease.
According to current understanding, as Dr. Kellermayer told GI & Hepatology News, most autoimmune disorders, CD included, develop in people with a genetic predisposition after serial environmental insults between conception and young adulthood. “As opposed to single-gene-associated genetic disorders, autoimmune diseases are linked to several hundred genes in which subtle anomalies can work in concert to predispose someone to a certain disorder,” he said. “We hope our findings will guide the development of personalized treatments based on the disease location at diagnosis to advance precision medicine.”
CD cases
Eight cases of SB-CD and 11 of C-CD met the inclusion criteria. Mean age at CD diagnosis was about 11 years for both subtypes, while 36.3% of patients with C-CD were female vs 25% of those with SB-CD. Ethnicity was 72.2% White in the C-CD group and 87.5% in the SB-CD group.
As to the main ileocolonic locations according to the Paris Classification of pediatric inflammatory bowel disease, 54.5% in the C-CD group had involvement at L2 and 45.5% at L3. In SB-CD cases, 100% had disease at L4b, 37.5% at L4, and 50% at L1.
The researchers identified 115 single-nucleotide polymorphisms (SNPs) with a combined annotation-dependent depletion (CADD) score on Phil’s Read Editor (PHRED) of >10 that was associated with 97 genes. PHRED is a computer program measuring the quality of the identification of nucleobases generated by automated DNA sequencing and scores the deleteriousness of single-nucleotide variants. The identified genes in this study had a significantly (P < .01) different allele variation between C-CD and SB-CD.
Among the top 28 candidates was an SNP in the EFNA3 gene with a CADD score > 20 for differentiating between the two phenotypically distinct CD groups. Furthermore, the EFNA3 rs17723260 (predicted to be deleterious) was found to have a significantly lower allele frequency (4.5%) in C-CD compared with its allele frequency of 37.5% in SB-CD (chi square P = .0097).
“This finding indicates that EFNA3 might play a role in modulating colonic inflammation, in which a deleterious genetic defect might provide protection against colitis (and direct autoimmunity against the proximal small bowel) in the polygenic background of CD,” the investigators wrote.
EFNA3 has been linked to both CD and ulcerative colitis. Another four genes associated with the top five SNP candidates had already been connected with IBD or mammalian intestinal inflammation.
According to the authors, the biomedical literature and mouse model findings “implicate the translational relevance of our candidate gene compendium for directing colon- vs small-bowel–predominant CD development.” They hope the findings will be replicated in larger CD cohorts differentiated by disease location. “Our work may set the nidus for CD subtype–based precision medicine by guiding individualized treatment strategies,” they wrote.
This study was supported by the ProKIIDS Network of the Crohn’s and Colitis Foundation and the Public Health Service. It was also supported by the Wagner, Frugoni, and Klaasmeyer families’ Gutsy Kids Fund and by the DR and GL Laws Fund. The authors disclosed no conflicts of interest.
, a small analysis in Cellular and Molecular Gastroenterology and Hepatology suggests.
Richard Kellermayer, MD, PhD, professor of pediatrics in the Section of Pediatric Gastroenterology, Hepatology and Nutrition at Baylor College of Medicine in Houston, Texas, and colleagues compared the genetic makeup of patients based on their Crohn’s disease location — predominantly in the small bowel (L4) or predominantly in the colon (L2 and/or L3). They then generated bipartite networks of susceptibility genes to study the polygenic background of the disease subtypes. They hypothesize that such networks may govern where a patient develops Crohn’s disease.
According to current understanding, as Dr. Kellermayer told GI & Hepatology News, most autoimmune disorders, CD included, develop in people with a genetic predisposition after serial environmental insults between conception and young adulthood. “As opposed to single-gene-associated genetic disorders, autoimmune diseases are linked to several hundred genes in which subtle anomalies can work in concert to predispose someone to a certain disorder,” he said. “We hope our findings will guide the development of personalized treatments based on the disease location at diagnosis to advance precision medicine.”
CD cases
Eight cases of SB-CD and 11 of C-CD met the inclusion criteria. Mean age at CD diagnosis was about 11 years for both subtypes, while 36.3% of patients with C-CD were female vs 25% of those with SB-CD. Ethnicity was 72.2% White in the C-CD group and 87.5% in the SB-CD group.
As to the main ileocolonic locations according to the Paris Classification of pediatric inflammatory bowel disease, 54.5% in the C-CD group had involvement at L2 and 45.5% at L3. In SB-CD cases, 100% had disease at L4b, 37.5% at L4, and 50% at L1.
The researchers identified 115 single-nucleotide polymorphisms (SNPs) with a combined annotation-dependent depletion (CADD) score on Phil’s Read Editor (PHRED) of >10 that was associated with 97 genes. PHRED is a computer program measuring the quality of the identification of nucleobases generated by automated DNA sequencing and scores the deleteriousness of single-nucleotide variants. The identified genes in this study had a significantly (P < .01) different allele variation between C-CD and SB-CD.
Among the top 28 candidates was an SNP in the EFNA3 gene with a CADD score > 20 for differentiating between the two phenotypically distinct CD groups. Furthermore, the EFNA3 rs17723260 (predicted to be deleterious) was found to have a significantly lower allele frequency (4.5%) in C-CD compared with its allele frequency of 37.5% in SB-CD (chi square P = .0097).
“This finding indicates that EFNA3 might play a role in modulating colonic inflammation, in which a deleterious genetic defect might provide protection against colitis (and direct autoimmunity against the proximal small bowel) in the polygenic background of CD,” the investigators wrote.
EFNA3 has been linked to both CD and ulcerative colitis. Another four genes associated with the top five SNP candidates had already been connected with IBD or mammalian intestinal inflammation.
According to the authors, the biomedical literature and mouse model findings “implicate the translational relevance of our candidate gene compendium for directing colon- vs small-bowel–predominant CD development.” They hope the findings will be replicated in larger CD cohorts differentiated by disease location. “Our work may set the nidus for CD subtype–based precision medicine by guiding individualized treatment strategies,” they wrote.
This study was supported by the ProKIIDS Network of the Crohn’s and Colitis Foundation and the Public Health Service. It was also supported by the Wagner, Frugoni, and Klaasmeyer families’ Gutsy Kids Fund and by the DR and GL Laws Fund. The authors disclosed no conflicts of interest.
, a small analysis in Cellular and Molecular Gastroenterology and Hepatology suggests.
Richard Kellermayer, MD, PhD, professor of pediatrics in the Section of Pediatric Gastroenterology, Hepatology and Nutrition at Baylor College of Medicine in Houston, Texas, and colleagues compared the genetic makeup of patients based on their Crohn’s disease location — predominantly in the small bowel (L4) or predominantly in the colon (L2 and/or L3). They then generated bipartite networks of susceptibility genes to study the polygenic background of the disease subtypes. They hypothesize that such networks may govern where a patient develops Crohn’s disease.
According to current understanding, as Dr. Kellermayer told GI & Hepatology News, most autoimmune disorders, CD included, develop in people with a genetic predisposition after serial environmental insults between conception and young adulthood. “As opposed to single-gene-associated genetic disorders, autoimmune diseases are linked to several hundred genes in which subtle anomalies can work in concert to predispose someone to a certain disorder,” he said. “We hope our findings will guide the development of personalized treatments based on the disease location at diagnosis to advance precision medicine.”
CD cases
Eight cases of SB-CD and 11 of C-CD met the inclusion criteria. Mean age at CD diagnosis was about 11 years for both subtypes, while 36.3% of patients with C-CD were female vs 25% of those with SB-CD. Ethnicity was 72.2% White in the C-CD group and 87.5% in the SB-CD group.
As to the main ileocolonic locations according to the Paris Classification of pediatric inflammatory bowel disease, 54.5% in the C-CD group had involvement at L2 and 45.5% at L3. In SB-CD cases, 100% had disease at L4b, 37.5% at L4, and 50% at L1.
The researchers identified 115 single-nucleotide polymorphisms (SNPs) with a combined annotation-dependent depletion (CADD) score on Phil’s Read Editor (PHRED) of >10 that was associated with 97 genes. PHRED is a computer program measuring the quality of the identification of nucleobases generated by automated DNA sequencing and scores the deleteriousness of single-nucleotide variants. The identified genes in this study had a significantly (P < .01) different allele variation between C-CD and SB-CD.
Among the top 28 candidates was an SNP in the EFNA3 gene with a CADD score > 20 for differentiating between the two phenotypically distinct CD groups. Furthermore, the EFNA3 rs17723260 (predicted to be deleterious) was found to have a significantly lower allele frequency (4.5%) in C-CD compared with its allele frequency of 37.5% in SB-CD (chi square P = .0097).
“This finding indicates that EFNA3 might play a role in modulating colonic inflammation, in which a deleterious genetic defect might provide protection against colitis (and direct autoimmunity against the proximal small bowel) in the polygenic background of CD,” the investigators wrote.
EFNA3 has been linked to both CD and ulcerative colitis. Another four genes associated with the top five SNP candidates had already been connected with IBD or mammalian intestinal inflammation.
According to the authors, the biomedical literature and mouse model findings “implicate the translational relevance of our candidate gene compendium for directing colon- vs small-bowel–predominant CD development.” They hope the findings will be replicated in larger CD cohorts differentiated by disease location. “Our work may set the nidus for CD subtype–based precision medicine by guiding individualized treatment strategies,” they wrote.
This study was supported by the ProKIIDS Network of the Crohn’s and Colitis Foundation and the Public Health Service. It was also supported by the Wagner, Frugoni, and Klaasmeyer families’ Gutsy Kids Fund and by the DR and GL Laws Fund. The authors disclosed no conflicts of interest.
FROM CELLULAR AND MOLECULAR GASTROENTEROLOGY AND HEPATOLOGY