Ultra-rare genetic disorders can provide proof of concept for efficacy of targeted therapeutics and reveal pathogenic mechanisms relevant to more common conditions. Juvenile polyposis of infancy (JPI) is caused by microdeletions in chromosome 10 that result in haploinsufficiency of two tumor suppressor genes: phosphatase and tensin homolog deleted on chromosome 10 (PTEN) and bone morphogenetic protein receptor type IA (BMPR1A). Loss of PTEN and BMPR1A results in a much more severe phenotype than deletion of either gene alone, with infantile onset pan-enteric polyposis and a high mortality rate. No effective pharmacological therapy exists. A multi-center cohort analysis was performed to characterize phenotype and investigate the therapeutic effect of mammalian target of rapamycin (mTOR) inhibition (adverse events, disease progression, time to colectomy and mortality) in patients with JPI. Among 25 JPI patients identified (mean age of onset 13 months), seven received mTOR inhibitors (everolimus, n = 2; or sirolimus, n = 5). Treatment with an mTOR inhibitor reduced the risk of colectomy (hazard ratio = 0.27, 95% confidence interval = 0.07–0.954, P = 0.042) and resulted in significant improvements in the serum albumin level (mean increase = 16.3 g/l, P = 0.0003) and hemoglobin (mean increase = 2.68 g/dl, P = 0.0077). Long-term mTOR inhibitor treatment was well tolerated over an accumulated follow-up time of 29.8 patient years. No serious adverse events were reported. Early therapy with mTOR inhibitors offers effective, pathway-specific and personalized treatment for patients with JPI. Inhibition of the phosphoinositol-3-kinase–AKT–mTOR pathway mitigates the detrimental synergistic effects of combined PTEN–BMPR1A deletion. This is the first effective pharmacological treatment identified for a hamartomatous polyposis syndrome.

Juvenile polyposis syndrome is a rare autosomal dominant condition characterized by multiple hamartomatous polyps throughout the gastrointestinal tract. Juvenile polyposis of infancy is a generalized severe form of juvenile polyposis syndrome associated with a poor prognosis. A 47-month-old female infant presented initially with gastrointestinal bleeding and protein-losing enteropathy at 4 months of age. At the age of 12 months, the condition worsened, requiring albumin infusions every 24 to 48 hours and red blood cell transfusions every 15 days. Upper gastrointestinal endoscopy, colonoscopy, and small-bowel enteroscopy revealed diffuse polyposis that was treated with multiple endoscopic polypectomies. Despite subtotal colectomy with ileorectal anastomosis, protein-losing enteropathy and bleeding persisted, requiring continued blood transfusions and albumin infusions. A chromosomal microarray revealed a single allele deletion in chromosome 10q23, involving both the PTEN and BMPR1A genes. Loss of PTEN function is associated with an increased activation of the protein kinase B (AKT)/mammalian target of rapamycin (mTOR) pathway involved in cell proliferation. Treatment with sirolimus, an mTOR inhibitor, was initiated with the aim of inhibiting polyp growth. Soon after initiation of treatment with sirolimus, blood and albumin infusions were no longer needed and resulted in improved patient growth and quality of life. This case represents the first detailed report of successful drug therapy for life-threatening juvenile polyposis of infancy.

Arcucci MS, et al. Pediatr Gastroenterol Hepatol Nutr. 2022 May;25(3):218-227. https://doi.org/10.5223/pghn.2022.25.3.218

There is little data on the experience of managing pediatric Intestinal Failure (IF) in Latin America. This study aimed to identify and describe the current organization and practices of the IF teams in Latin America and the Caribbean. An online survey was sent to inquire about the existence of IF teams that managed children on home parenteral nutrition (HPN). Our questionnaire was based on a previously published European study with a similar goal. Twenty-four centers with pediatric IF teams in eight countries completed the survey, representing a total number of 316 children on HPN. The median number of children on parenteral nutrition (PN) at home per team was 5.5 (range 1–50). Teams consisted of the following members: pediatric gastroenterologist and a pediatric surgeon in all teams, dietician (95.8%), nurse (91.7%), social worker (79.2%), pharmacist (70.8%), oral therapist (62.5%), psychologist (58.3%), and physiotherapist (45.8%). The majority of the centers followed international standards of care on vascular access, parenteral and enteral nutrition, and IF medical and surgical management, but a significant percentage reported inability to monitor micronutrients, like vitamins A (37.5%), E (41.7%), B1 (66.7%), B2 (62.5%), B6 (62.5%), active B12 (58.3%); and trace elements—including zinc (29.2%), aluminum (75%), copper (37.5%), chromium (58.3%), selenium (58.3%), and manganese (58.3%). Conclusion: There is wide variation in how IF teams are structured in Latin America—while many countries have well-established Intestinal rehabilitation programs, a few do not follow international standards. Many countries did not report having an IF team managing pediatric patients on HPN.