Association of Clinical Biochemists in Ireland Annual Conference

Cystinuria is an autosomal recessive metabolic disorder characterized by defective reabsorption of cystine and dibasic amino acids (lysine, arginine, and ornithine) in the proximal renal tubules and small intestine.The condition involves mutations in two key genes: SLC3A1 and SLC7A9.The SLC3A1 gene encodes the rBAT protein, while the SLC7A9 gene encodes the b0,+AT protein.Cystinuria is classified into three types based on genetic mutations: Type A (SLC3A1 defects), Type B (SLC7A9 defects), and Type AB (mutations in both genes).Cystinuria is characterised by persistently elevated levels of cystine in the urine, with or without urinary cystine stones formation.In contrast, transient neonatal cystinuria (TNC) is observed in newborns with initially high cystine levels that decrease over the first two years of life due to immature renal amino acid transport.Confirmatory diagnosis involves measuring urinary amino acid levels, with cystine typically exceeding 1000 mol/ g creatinine.In this report, we describe a case of TNC that developed in a 15-month-old boy who was born extremely premature at 24 weeks and 3 days gestation.Immediately after birth, he required intubation and mechanical ventilation due to respiratory distress and poor Apgar score.At 40 days old, the boy was re-admitted with a non-functioning ileostomy, necessitating a stoma revision and adhesion lysis.During this admission, he experienced multi-system dysfunction including eA240