Neonatal-onset citrin deficiency: long-term outcomes in four cases and identification of a novel variant.

Background: Citrin deficiency (CD), caused by mutations in the SLC25A13 gene, is a rare autosomal recessive urea cycle disorder with variable clinical presentations depending on age. These include neonatal intrahepatic cholestasis (NICCD), failure to thrive with dyslipidemia, and adult-onset type II citrullinemia. Patients with NICCD typically present with transient intrahepatic cholestasis in infancy, which often resolves spontaneously by one year of age; however, some may progress to severe complications later in life.

Case presentation: Four cases diagnosed with NICCD phenotype are presented. All patients presented with neonatal cholestasis, hypertransaminasemia, galactosuria, and elevated citrulline levels. Molecular analysis identified three disease-causing variants: two previously reported variants, c.955C>T (p.Arg319*) and c.74C>A (p.Ala25Glu), and a novel variant, c.1359G>T (p.Lys453Asn). Treatment included a galactose-free formula, medium-chain triglycerides, and nutritional supplementation, resulting in biochemical and clinical improvement. All patients in our series exhibited a milder clinical course, with no episodes of hyperammonemia or hypoglycemia, no progression to liver failure, and favorable long-term outcomes with dietary management. During a long-term follow-up period ranging from 7 to 11 years, no severe complications were observed. Notably, one patient developed a recurrence of cataract, emphasizing the importance of lifelong dietary adherence and regular eye examinations.

Conclusions: The findings in this paper further expand the genotypic spectrum and genotype-phenotype correlations of CD. Lifelong follow-up is recommended, including ocular examination.