Infantile nephrocalcinosis with chronic diarrhea

Area of Science:

• Pediatric Nephrology
• Medical Genetics
• Gastroenterology

Background:

• Nephrocalcinosis and hyperoxaluria can present in infants, sometimes linked to genetic factors.
• Congenital lactase deficiency (CLD) is a rare disorder affecting lactose digestion.
• Hypercalciuria and hyperoxaluria can contribute to kidney stone formation and renal damage.

Purpose of the Study:

• To investigate the underlying cause of nephrocalcinosis, hypercalciuria, and hyperoxaluria in an infant.
• To determine the genetic basis for the observed metabolic derangements.
• To assess the impact of dietary intervention on clinical symptoms and biochemical markers.

Main Methods:

• Clinical case presentation of a 3-month-old infant with relevant symptoms.
• Biochemical analysis including urine and stool studies.
• Whole exome sequencing (WES) for genetic variant identification.
• Dietary intervention with lactose restriction and monitoring of outcomes.

Main Results:

• The infant presented with dysuria, hematuria, chronic diarrhea, hypercalciuria, and nephrocalcinosis.
• Stool analysis revealed reducing sugars, and symptoms improved with lactose restriction.
• Whole exome sequencing identified a homozygous variant in the LCT gene (CLD) and a heterozygous variant in ADCY10 (absorptive hypercalciuria).
• Hyperoxaluria resolved with dietary changes, while hypercalciuria persisted.

Conclusions:

• The findings suggest an enteric hyperoxaluria phenotype secondary to congenital lactase deficiency.
• Genetic variants in LCT and ADCY10 contribute to the complex presentation.
• Dietary management is crucial for addressing metabolic disturbances in infants with genetic disorders affecting nutrient absorption.