Novel Compound Heterozygote Mutations of the SLC25A13 Gene in an Infant with Neonatal-onset Type II Citrullinemia Detected by Newborn Mass Screening

ABSTRACT

Citrin deficiency caused by the SLC25A13 gene mutations is associated with both neonatal-onset type II citrullinemia (CTLN2), also known as neonatal intrahepatic cholestasis caused by citrin deficiency and adult-onset CTLN2. Neonatal-onset CTLN2 is an autosomal recessive disorder characterized by poor growth, intrahepatic cholestasis, and increased serum citrulline. A 16-days old infant with hyperammonemia was referred for evaluation of increased plasma citrulline diagnosed using tandem mass spectrometry. Blood amino acid analysis showed significant elevation of citrulline. Mild elevation in serum galactose levels had been found. DNA analysis of the SLC25A13 gene in this patient showed two novel compound heterozygous mutations, c.221C>T in exon4 and c.1645C in exon16 (p.[Ser74Phe]+[Gln549X]). We suggest that infants with a high serum citrulline level on a tandem mass screening test are candidates for gene analysis and blood amino acid analysis for neonatal-onset CTLN2.