6-mercaptopurine metabolite levels in children with inflammatory bowel disease.

OBJECTIVES: Some authors suggest that efficacy of 6-mercaptopurine (6-MP) in patients with inflammatory bowel disease correlates with circulating 6-thioguanine (6-TG) levels more than 235 pmol/8 x 10(8) red blood cells. The authors evaluated the relation between 6-MP metabolite levels and disease activity in children and adolescents with inflammatory bowel disease. METHODS: Clinical status and hematologic and hepatic parameters were determined in 101 children with inflammatory bowel disease from a single center and compared with 6-MP metabolite levels. RESULTS: There was a trend for higher 6-TG levels among patients in remission than among those with active disease (217 vs. 173); however the difference was not statistically significant ( P = 0.09). The likelihood of therapeutic response did not increase significantly at 6-TG levels greater than 235 pmol/8 x 10(8) red blood cells (odds ratio 1.7; P = 0.1). In the current study, 58% of patients in remission had 6-TG levels less than 235. However, serial measurements of 6-MP metabolite levels in 50 patients with active disease showed that increasing 6-TG levels correlated significantly with disease remission in patients followed up longitudinally ( P = 0.04). Leukopenia was significantly associated with high 6-TG levels ( P = 0.03) but not with clinical response ( P = 0.2). CONCLUSIONS: These data suggest that the target range of 6-TG levels previously described by others did not apply to 58% of the pediatric patients with IBD in remission. However, serial monitoring of 6-MP metabolite levels in individual patients with active disease should allow dose escalation and induction of remission while minimizing the risk of toxicity.

A frameshift mutation in NOD2 associated with susceptibility to Crohn's disease.

Crohn's disease is a chronic inflammatory disorder of the gastrointestinal tract, which is thought to result from the effect of environmental factors in a genetically predisposed host. A gene location in the pericentromeric region of chromosome 16, IBD1, that contributes to susceptibility to Crohn's disease has been established through multiple linkage studies, but the specific gene(s) has not been identified. NOD2, a gene that encodes a protein with homology to plant disease resistance gene products is located in the peak region of linkage on chromosome 16 (ref. 7). Here we show, by using the transmission disequilibium test and case-control analysis, that a frameshift mutation caused by a cytosine insertion, 3020insC, which is expected to encode a truncated NOD2 protein, is associated with Crohn's disease. Wild-type NOD2 activates nuclear factor NF-kappaB, making it responsive to bacterial lipopolysaccharides; however, this induction was deficient in mutant NOD2. These results implicate NOD2 in susceptibility to Crohn's disease, and suggest a link between an innate immune response to bacterial components and development of disease.

Linkage heterogeneity for the IBD1 locus in Crohn's disease pedigrees by disease onset and severity.

BACKGROUND & AIMS: There is evidence for the IBD1 Crohn's disease (CD) susceptibility locus on chromosome 16 in several but not all populations studied. Genetic and phenotypic heterogeneity may underlie ability to replicate IBD1. We determined if age and severity stratification could identify a clinical subgroup at risk for IBD1. METHODS: Linkage analysis at microsatellites spanning chromosome 16 was performed in 2 groups of CD pedigrees: group 1, 57 pedigrees with at least one affected relative classified as having "severe" disease, by history of surgical resection or immunomodulator therapy, and with disease diagnosed before age 22; and group 2, 33 pedigrees with no history of early-onset, severe CD. RESULTS: Group 1 pedigrees demonstrated genomewide significant linkage evidence for the IBD1 locus (nonparametric multipoint logarithm of the odds [Mlod], 3.84; P = 1.3 x 10(-5)) with linkage evidence greater than all 90 pedigrees (Mlod, 2.12; P = 9.0 x 10(-4)). Group 2 pedigrees had near zero nonparametric 2-point and Mlod scores for the IBD1 region. Heterogeneity between groups 1 and 2 was significant (P = 0.002). CONCLUSIONS: Presence of early-onset, more severe CD identifies pedigrees at high risk for IBD1. These pedigrees will have more power to refine the IBD1 locus and identify the causative gene.

Oral tacrolimus treatment of severe colitis in children.

OBJECTIVE: To evaluate the efficacy of oral tacrolimus as an induction agent in steroid-refractory severe colitis. STUDY DESIGN: Open-label, multicenter trial of oral tacrolimus in patients with severe colitis. Patients not responding to conventional therapy received tacrolimus, 0.1 mg/kg/dose given twice a day, and the dosage was adjusted to achieve blood levels between 10 and 15 ng/mL. Response was defined as improvement in a number of clinical parameters (including abdominal pain, diarrhea, rectal bleeding, and cessation of transfusions). Patients who responded by 14 days continued to receive tacrolimus, and 6-mercaptopurine or azathioprine was added as a steroid-sparing agent 4 to 6 weeks after the tacrolimus was instituted. RESULTS: Fourteen patients were enrolled in the study. One patient elected to withdraw after 48 hours. Of the 13 remaining, 9 (69%) responded and were discharged. Tacrolimus was continued for 2 to 3 months in the responders, except for 1 patient who was given tacrolimus for 11 months. After 1 year of follow-up, only 5 (38%) patients were receiving maintenance therapy; the other 4 responders had undergone colectomy. CONCLUSION: Although tacrolimus is effective induction therapy for severe ulcerative or Crohn's colitis, fewer than 50% of patients treated will successfully achieve a long-term remission.

Is lactobacillus GG helpful in children with Crohn's disease? Results of a preliminary, open-label study.

BACKGROUND: Lactobacillus GG is a safe probiotic bacterium known to transiently colonize the human intestine. It has been found to be useful in treatment of several gastrointestinal conditions characterized by increased gut permeability. In the current study, the efficacy of Lactobacillus GG was investigated in children with Crohn's disease. METHODS: In this open-label pilot evaluation viewed as a necessary preliminary step for a possible subsequent randomized placebo-controlled trial, four children with mildly to moderately active Crohn's disease were given Lactobacillus GG (10(10) colony-forming units [CFU]) in enterocoated tablets twice a day for 6 months. Changes in intestinal permeability were measured by a double sugar permeability test. Clinical activity was determined by measuring the pediatric Crohn's disease activity index. RESULTS: There was a significant improvement in clinical activity 1 week after starting Lactobacillus GG, which was sustained throughout the study period. Median pediatric Crohn's disease activity index scores at 4 weeks were 73% lower than baseline. Intestinal permeability improved in an almost parallel fashion. CONCLUSIONS: Findings in this pilot study show that Lactobacillus GG may improve gut barrier function and clinical status in children with mildly to moderately active, stable Crohn's disease. Randomized, double-blind, placebo-controlled trials are warranted for a final assessment of the efficacy of Lactobacillus GG in Crohn's disease.

Chronic recurrent multifocal osteomyelitis associated with chronic inflammatory bowel disease in children.

Chronic recurrent multifocal osteomyelitis (CRMO) is a rare disease of children characterized by aseptic inflammation of the long bones and clavicles. No infectious etiology has been identified, and CRMO has been associated with a number of autoimmune diseases (including Wegener's granulomatosis and psoriasis). The relationship between CRMO and inflammatory bowel disease is poorly described. Through an internet bulletin board subscribed to by 500 pediatric gastroenterologists, we identified six inflammatory bowel disease patients (two with ulcerative colitis, four with Crohn's colitis) with confirmed CRMO. In all cases, onset of the bony lesions preceded the onset of bowel symptoms by as much as five years. Immunosuppressive therapy for the bowel disease generally resulted in improvement of the bone inflammation. Chronic recurrent multifocal osteomyelitis should be considered in any inflammatory bowel disease patient with unexplained bone pain or areas of uptake on bone scan. CRMO may be a rare extraintestinal manifestation of inflammatory bowel disease; alternatively, certain individuals may be genetically predisposed to the development of both diseases.

American families with Crohn's disease have strong evidence for linkage to chromosome 16 but not chromosome 12.

BACKGROUND & AIMS: Two European genome-wide screens for inflammatory bowel disease have identified two significant regions of linkage on chromosomes 16 (IBD1) and 12 (IBD2) and two regions with suggestive levels of significance (chromosomes 3p and 7q). The aim of this study was to determine if there was evidence for linkage to these regions in non-Jewish and Ashkenazi Jewish families multiplex for Crohn's disease from the United States. METHODS: One hundred forty-eight affected relative pairs, 34% Ashkenazim, were genotyped with 10-14 highly polymorphic markers overlying each candidate region. Nonparametric multipoint and two-point linkage analyses were performed. RESULTS: Significant evidence for replication of linkage was found only for the chromosome 16 locus, IBD1, maximal at D16S769 (nonparametric linkage score [NPL], 2.49; P = 0.007). Analysis by ethnicity showed stronger evidence for Ashkenazim (D16S769; NPL = 2. 52; P = 0.007) than for non-Jewish white populations (D16S401; NPL = 1.40; P = 0.082). There was no significant evidence for replication on chromosome 12 (IBD2). Minimal evidence for extension of linkage evidence was observed for the chromosomes 3p and 7q regions. CONCLUSIONS: American families, particularly Ashkenazim, have significant evidence for the Crohn's disease susceptibility locus, IBD1, on chromosome 16, but not for IBD2 on chromosome 12.

Safety of azathioprine and 6-mercaptopurine in pediatric patients with inflammatory bowel disease.

BACKGROUND & AIMS: Azathioprine (AZA) and 6-mercaptopurine (6-MP) are used in pediatric patients with ulcerative colitis and Crohn's disease to reduce disease activity, maintain remission, prevent relapse, and lower corticosteroid dosage, but their long-term side effects remain to be studied. The aim of this study was to analyze the safety of AZA and 6-MP and steroid reduction in this age group. METHODS: The investigators' database identified 118 patients who received either drug; 23 were excluded (single visit, noncompliance, or therapy < 1 week), leaving 95 patients, with a mean (+/-SD) age of 14.2 +/- 4.4 years. Medical files were reviewed for adverse side effects: fever, pancreatitis, infections, gastrointestinal intolerance, aminotransferase level increase, leukopenia, and thrombocytopenia. Prednisone doses before and after immunomodulatory therapy were compared. RESULTS: AZA or 6-MP was tolerated in 51 of 95 patients (54%) without adverse reaction; 27 of 95 (28%) experienced side effects that responded to dose reduction (23 patients) or spontaneously (4 patients), most commonly increased aminotransferase level (13.7%). Cessation of therapy was needed in 17 of 95 patients (18%), including recurrent fever (4), pancreatitis (4), gastrointestinal intolerance (4), and recurrent infections (3). Mean prednisone dose decreased from 24.3 to 8.6 mg/day. CONCLUSIONS: AZA and 6-MP were well tolerated in 82% of patients; of these, prednisone reduction occurred in 87%. However, 18% required discontinuation because of hypersensitivity or infectious side effects.

Identification of novel susceptibility loci for inflammatory bowel disease on chromosomes 1p, 3q, and 4q: evidence for epistasis between 1p and IBD1.

The idiopathic inflammatory bowel diseases, Crohn's disease (CD) and ulcerative colitis (UC), are chronic, frequently disabling diseases of the intestines. Segregation analyses, twin concordance, and ethnic differences in familial risks have established that CD and UC are complex, non-Mendelian, related genetic disorders. We performed a genome-wide screen using 377 autosomal markers, on 297 CD, UC, or mixed relative pairs from 174 families, 37% Ashkenazim. We observed evidence for linkage at 3q for all families (multipoint logarithm of the odds score (MLod) = 2.29, P = 5.7 x 10(-4)), with greatest significance for non-Ashkenazim Caucasians (MLod = 3.39, P = 3.92 x 10(-5)), and at chromosome 1p (MLod = 2.65, P = 2.4 x 10(-4)) for all families. In a limited subset of mixed families (containing one member with CD and another with UC), evidence for linkage was observed on chromosome 4q (MLod = 2.76, P = 1.9 x 10(-4)), especially among Ashkenazim. There was confirmatory evidence for a CD locus, overlapping IBD1, in the pericentromeric region of chromosome 16 (MLod = 1.69, P = 2.6 x 10(-3)), particularly among Ashkenazim (MLod = 1.51, P = 7.8 x 10(-3)); however, positive MLod scores were observed over a very broad region of chromosome 16. Furthermore, evidence for epistasis between IBD1 and chromosome 1p was observed. Thirteen additional loci demonstrated nominal (MLod > 1.0, P < 0.016) evidence for linkage. This screen provides strong evidence that there are several major susceptibility loci contributing to the genetic risk for CD and UC.

Bone mineral density assessment in children with inflammatory bowel disease.

BACKGROUND & AIMS: Children with inflammatory bowel disease (IBD) are at risk for osteoporosis because of undernutrition, delayed puberty, and prolonged corticosteroid use. The aim of this study was to compare bone mineral density (BMD) in children with IBD with that in normal children and to assess the effects of nutritional and hormonal factors and corticosteroid dosages on BMD. METHODS: One hundred sixty-two subjects (99 with IBD and 63 healthy sibling controls) were enrolled. Patients underwent anthropometric assessment, pubertal staging, bone age radiography, and BMD assessment by dual energy x-ray absorptiometry of the lumbar spine, femoral neck, and radius. Laboratory evaluations included serum calcium, phosphate, alkaline phosphatase, 25-hydroxyvitamin D, 1,25-dihydroxyvitamin D, parathyroid hormone, osteocalcin, urinary N-telopeptides, albumin, insulin-like growth factor I, and testosterone or estradiol. Cumulative corticosteroid doses were calculated. RESULTS: BMD Z scores at the lumbar spine and femoral neck were lower in patients with IBD, and lower in those with Crohn's disease compared with those with ulcerative colitis. Low BMD persisted after correction for bone age in girls with Crohn's disease (lumbar spine, P = 0.004; femoral neck, P = 0.002). Cumulative corticosteroid dose was a significant predictor of reduced BMD. BMD did not correlate with measures of calcium homeostasis, except elevated serum phosphate and urine calcium levels in girls. CONCLUSIONS: Low BMD occurs in children with IBD (more in Crohn's disease than in ulcerative colitis), especially pubertal and postpubertal girls. Cumulative corticosteroid dose is a predictor of low BMD, but other factors in Crohn's disease remain undetermined.

Differences in the management of inflammatory bowel disease in children and adolescents compared to adults.

Managing IBD in children and adolescents requires attention to issues unique to these age groups. The spectrum of presenting signs and symptoms is broad and often, subtle. Physician awareness of intestinal and extra-intestinal features prompts earlier diagnosis and intervention. The focus of treatment is not limited to intestinal symptoms, but also involves assessing weight and height gains, sexual maturation, extra-intestinal manifestations and psychosocial well-being. Differences in selecting drugs for pediatric versus adult patients are based on: 1. lack of prospective trials establishing effective doses for different ages; 2. inability to swallow capsules; 3. importance of nutrition in promoting growth; 4. paucity of data regarding the long-term safety of medications; 5. untoward cosmetic effects of corticosteroids, and 6. the need to develop coping mechanisms for a chronic illness. While sulfasalazine and mesalamine are useful in mild disease, corticosteroids are necessary for moderate and severe disease. Metronidazole and ciprofloxacin are effective in perianal CD. Elemental and polymeric formulas induce and maintain remission in active CD and reverse growth failure. Immunomodulatory agents (azathioprine and 6-mercaptopurine) enable physicians to reduce steroids and hospitalization. In practice, combination therapy is recommended to control symptoms and limit drug-induced side effects.

Use of barbiturates in the treatment of cyclic vomiting during childhood.

BACKGROUND: Cyclic vomiting is an uncommon disorder that can be described as recurrent, self-limiting, fairly uniform episodes of intractable nausea and vomiting with no identifiable organic cause, separated by symptom-free intervals. There is no established therapeutic regimen for this disorder. METHODS: Fourteen children referred to the Pediatric Gastroenterology Clinic were diagnosed with cyclic vomiting from May 1984 to January 1995. Vomiting, the predominant symptom, was present in all children and was severe enough to require hospitalization in 11. Associated symptoms included abdominal ain, headache, nausea, aura, and fever. Diagnostic studies were done to rule out organic causes as indicated in individual patients. Daily phenobarbital was prescribed in all 14 patients. The dose ranged from 30 to 120 mg/hs, (mean 2 mg.kg-1.day-1), with a median dose of 60 mg/hs [corrected]. Prior therapy with propranolol (3 patients) and butalbital (2 patients) had been ineffective. RESULTS: Eleven patients had complete resolution of their symptoms, and 3 patients had marked improvement in their symptoms with infrequent attacks of reduced severity. The only side effects associated with long-term phenobarbital therapy were behavioral in nature, namely hyperactivity and disruptive behavior at school. CONCLUSIONS: The results of our series of 14 patients, all of whom received barbiturates, support the usefulness of this therapeutic approach. Hence we feel that daily low-dose phenobarbital therapy is a safe and effective therapy in preventing episodes of cyclic vomiting in children.

Confirmation of a susceptibility locus for Crohn's disease on chromosome 16.

SUMMARY: : Crohn's disease and ulcerative colitis are related complex genetic disorders producing chronic intestinal inflammation. A susceptibility locus for Crohn's disease, IBDI (inflammatory bowel disease), has been implicated on chromosome 16. To evaluate IBDI in a different population using alternative methodology, we tested markers in the region of IBDI. Seventy-two relative pairs with Crohn's disease only, 23 mixed relative pairs (one relative having Crohn's disease, the other, ulcerative colitis), and 5 relative pairs with ulcerative colitis were genotyped in the region of IBDI. Our population consisted of white Americans, with 29% of families of Ashkenazi Jewish descent. Among the Crohn's disease pairs, we found evidence for linkage at IBDI using multipoint analysis, p = 0.0082. Negative linkage scores were obtained for mixed and ulcerative colitis-only relative pairs. For the entire data set, including mixed relative pairs and relative pairs with ulcerative colitis, there was no significant evidence of linkage. No difference was observed in the evidence of linkage between Jewish and non-Jewish families. Our studies confirm that IBDI represents a susceptibility locus for Crohn's disease, but not ulcerative colitis.

Molecular analysis of the fructose transporter gene (GLUT5) in isolated fructose malabsorption.

Fructose, a naturally occurring monosaccharide, is increasingly used as an added sweetener in processed foods in the form of high fructose corn syrup. Increased fructose intake combined with the identification of children with clinical evidence of isolated fructose malabsorption (IFM) has stimulated interest in possible disorders of fructose absorption. The intestinal absorption of fructose is carried out by the facilitative hexose transporter, which has been designated as GLUT5. Functional properties and tissue distribution of GLUT5 suggest that IFM might be due to mutations in the GLUT5 gene. To test this hypothesis, we screened the GLUT5 gene for mutations in a group of eight patients with IFM and in one subject with global malabsorption, as compared with 15 healthy parents of subjects and up to 6 unrelated controls. No mutations were found in the protein coding region of this gene in any of the subjects. A single G to A substitution in the 5' untranslated region of exon 1 was identified in the subject with global malabsorption. This subject and her healthy mother were heterozygous for the variant sequence, suggesting that it was unlikely to be clinically significant. In addition, sequence analysis of each of the 12 GLUT5 exons was performed in the index case and confirmed the negative single-strand conformation polymorphism findings. These studies demonstrate that IFM does not result from the expression of mutant GLUT5 protein.

Ulcerative colitis in children.

Chronic nonspecific ulcerative colitis remains a disease of unknown etiology, although much new information continues to be gleaned from basic research and clinical trials. In most instances, ulcerative colitis responds to medical therapy. Selecting appropriate drug therapy for a specific child depends on the extent and severity of the colitis. This article summarizes the clinical information, diagnostic studies, and approaches to management that should be considered when evaluating a child for ulcerative colitis.