Table 1.

Summary of relevant data for each case presented.

	Case 1	Case 2	Case 3	Case 4
Birth history	Female infant born at 39/40 Antenatal polyhydramnios and echogenic bowel. Bowel obstruction suspected but ruled out after birth	Female infant born at 35/40 Consanguineous parents. Antenatal polyhydramnios. Low birth weight	Male infant born at 37/40 Consanguineous parents	Born at 36/40 to consanguineous parents. Antenatal polyhydramnios and suspected bowel obstruction
Presentation	Hyponatremia, hypokalemia, persistent metabolic acidosis, and elevated serum levels of renin/aldosterone in the first week of life. Initially thought to suffer from polyuria which was later found to be watery diarrhea. Commenced on electrolyte supplements and referred to Nephrology for suspected Bartter syndrome. Renal pathology was excluded, and elevated stool chloride (116 mmol/L) was detected. CCD was suspected and referral to pediatric Gastroenterology unit. CCD diagnosis was confirmed, and sodium chloride and potassium chloride supplements were adjusted with normalization of sodium balance and acid/base status. Required gastrostomy insertion as unable to take supplements by mouth	Delayed motor milestones at age 2 months Multiple hospital admissions from the age of 7 months with watery diarrhea and vomiting. Worsening renal function and development of chronic kidney failure associated with episodes of severe dehydration. Bartter's syndrome suspected at age 20 months due to persistent hypochloremic, hypokalemic metabolic acidosis. Poor response to indomethacin, loperamide, and sodium/potassium supplementation. High stool chloride detected	14% weight loss, hyponatremia, and hypokalemia in first week of life. Chronic diarrhea with recurrent dehydration and failure to thrive. Elevated fecal chloride	No evidence of bowel obstruction after birth. Normal suction rectal biopsy ruling out Hirschsprung's disease Parents first concerned about watery stool at age 2 years. Two admissions with dehydration Stool sample revealed elevated fecal chloride (144 mmol/L). CCD was suspected, and oral supplementation with sodium chloride and potassium chloride commenced
Genetics	Homozygous for c.2024_2026dup;p (lle675dup) mutation in the SLC26A3 gene	c.1386G>A (W462X) mutation in the SLC26A3 gene	c.1386G>A homozygous SLC26A3 mutation	c.559G>T (p.Gly187) nonsense mutation in the SLC26A3 gene
Progress	Vomiting and worsening diarrhea from age 7 months. Initially, marginally elevated fecal calprotectin of 394 mg/kg (<50 mg/kg). Symptoms gradually progressed. Started to pass blood per rectum at age 10 months, and fecal calprotectin went up to 1,414 mg/kg	Persistent watery diarrhea and poor weight gain despite adequate supplementation of sodium and potassium chloride	Supplementation with sodium chloride and potassium chloride Referred at age 6 months in poor nutritional status requiring 8 weeks of parenteral nutrition due to poor enteral tolerance. Trial of butyrate supplementation failed to reduce high stool output	Remained well on supplementation with sodium and potassium chloride. No further hospital admissions and stabilization of stool output
IBD	Upper and lower gastrointestinal endoscopy showed chronic pancolitis with focal active inflammation and ulceration. After a primary immunodeficiency was ruled out, a course of prednisolone was commenced. Although symptoms improved, she had ongoing diarrhea with intermittent blood per rectum and persistently elevated fecal calprotectin. At age 15 months, second colonoscopy confirmed chronic inflammation throughout the colon, with granulomas and eosinophils	Upper and lower endoscopy revealed erythema and ulcers in colon. Histology revealed duodenitis and patchy focal active colitis	Upper and lower endoscopy aged 8 months: mild mucosal abnormalities with florid apoptotic debris in small bowel and mild inflammation of colon	Normal upper and lower endoscopy. No clinical, endoscopic, or histological evidence of IBD
Therapy	A second course of oral prednisolone was prescribed, and azathioprine was added to the medication. Bloody stools settled, and fecal calprotectin levels returned to normal	Supplementation of sodium chloride and potassium chloride together with calcium butyrate and amino acid-based feed Repeat OGD and colonoscopy 8 months later showed a mild chronic inactive gastritis only with resolved histological changes in small and large bowel	Weaned onto extensively hydrolyzed formula and intravenous fluids after 2 months of parenteral nutrition. Intravenous fluids stopped after 4 months. Repeat endoscopic assessment of the bowel was normal	Adjustment of sodium chloride and potassium chloride supplementation. Good weight gain. No IBD treatment required
Outcome	Azathioprine was discontinued at age 3 years following normal upper and lower endoscopy Currently, 4 years 6 months of age and well. On daytime supplementation with sodium chloride (15 mmol twice daily) and potassium chloride (7.5 mmol twice daily) and 400 ml of Dioralyte (two sachets) with added NaCl (53 mmol) and KCl (38 mmol) overnight (via gastrostomy)	Well at age 7 years on 20 mmol of sodium chloride (30% solution) three times a day and 30 mmol potassium chloride daily when family moved to another country. Now aged 10 and well	15 years of age. On normal diet and receiving 16 mmol of sodium chloride three times daily and 16 mmol of potassium chloride twice daily. Stable without clinical evidence of IBD	Transitioned well to the adult services at age 17 years. At the time of discharge on 20 mmol sodium chloride (30% solution) three times a day and 30 mmol potassium chloride three times daily. Currently 26 years of age and well