Phenotype and disease course of early-onset pediatric inflammatory bowel disease.

BACKGROUND: Early-onset (EO) pediatric inflammatory bowel diseases (IBD) seem to be more extensive than those with a later onset. To test this hypothesis, we examined the phenotype and disease course of patients with IBD diagnosis at 0 to 5 years, compared with the ranges 6 to 11 and 12 to 18 years. METHODS: Anatomic locations and behaviors were assessed according to Paris classification in 506 consecutive patients: 224 Crohn's disease, 245 ulcerative colitis, and 37 IBD-unclassified. RESULTS: Eleven percent of patients were in the range 0 to 5 years, 39% in 6 to 11 years, and 50% in 12 to 18 years. Ulcerative colitis was the most frequent diagnosis in EO-IBD and in 6- to 11-year-old group, whereas Crohn's disease was predominant in older children. A classification as IBD-unclassified was more common in the range 0 to 5 years compared with the other groups (P < 0.005). EO Crohn's disease showed a more frequent isolated colonic (P < 0.005) and upper gastrointestinal involvement than later-onset disease. Sixty-two percent of the patients in the 0 to 5 years range had pancolonic ulcerative colitis, compared with 38% of 6 to 11 years (P = 0.02) and 31% of 12-18 years (P = 0.002) range. No statistical difference for family history for IBD was found in the 3-year age groups. Therapies at the diagnosis were similar for all children. However, at latest follow-up, a significantly higher proportion of younger children were under steroids compared with older groups (P < 0.05). Surgical risk did not differ according to age. CONCLUSIONS: EO-IBD exhibits an extensive phenotype and benefit from aggressive treatment strategies, although surgical risk is similar to later-onset disease. A family history for IBD is not common in EO disease.

Variable phenotypic expression of chylomicron retention disease in a kindred carrying a mutation of the Sara2 gene.

Chylomicron retention disease is a recessive inherited disorder characterized by fat malabsorption and steatorrhea and is associated with failure to thrive in infancy. We describe a kindred carrying a mutation of Sara2 gene causing a chylomicron retention phenotype. The proband was a 5-month-old baby, born of consanguineous, apparently healthy parents from Morocco, with failure to thrive. There was a large quantity of fats in feces and malabsorption of fat-soluble vitamins. Intestinal biopsies showed a diffused enterocyte vacuolization with large cytosolic lipid droplets. Chylomicron retention disease or Anderson disease was hypothesized, and the Sara2 gene was analyzed by direct sequencing. Analysis of the Sara2 gene in the proband identified a 2-nucleotide homozygous deletion in exon 3 leading to a premature stop codon (c.75-76 del TG-L28fsX34). The father was heterozygous for the same mutation, whereas the proband's mother was homozygous, suggesting a variable phenotypic expression of the molecular defect. More studies are needed to understand the reasons of the phenotypic variability of the same molecular defect in the same family.

Thiopurine S-methyltransferase pharmacogenetics in a large-scale healthy Italian-Caucasian population: differences in enzyme activity.

AIMS: To investigate the influence of genotype, age and gender on the thiopurine S-methyltransferase (TPMT) phenotype in healthy Italian-Caucasian subjects. MATERIALS & METHODS: The study investigated the TPMT genotype and the TPMT phenotype of 943 healthy Italian-Caucasian subjects of different age and gender (age range: 0.08-68 years; 623 males 320 females). TPMT red blood cell activity was measured in all samples and genotype was determined for the TPMT alleles *2, *3A, *3B and *3C. RESULTS: TPMT activity levels in our whole population ranged from 1.6 up to 75.2 U/gHb. Significant TPMT activity differences between wild-type and heterozygous subjects were observed. We divided our TPMT activity into four categories according to our frequency distribution: low (0.1%), intermediate (32.9%), normal (60%) and high (7%), with arbitrary cut-off values of 8.0, 19.4 and 37.0 U/gHb, respectively. The whole population had a total of 94.5% of homozygous wild-type subjects, 5.4% heterozygous variants and one (0.1%) compound heterozygous variant TPMT*3B/*3C. The overall concordance rate between TPMT genotypes and phenotypes was 71.6%. The TPMT activity was significantly higher in wild-type children (0.08-17 years) than in wild-type adults (aged 18-68 years). Moreover, it was noted that wild-type infants from 0.08 to 5 years had a 9% higher average TPMT activity than the other wild-type groups, and only in children from 0.08 to 2 years was the TPMT activity higher in males than in females. CONCLUSION: The data obtained in this study show that genetic factors seem to be the major aspect in TPMT phenotype variability in adults, whilst, in children, other physiological factors should be taken into consideration when assessing the TPMT phenotype, such as age and gender.