Correlation between mutation of MDR3 gene exon 6 and parenteral nutrition-associated cholestasis of preterm infants

The aim of this study was to investigate the association between the mutation of multidrug resistance 3 (MDR3) exon 6 and parenteral nutrition-associated cholestasis (PNAC) in preterm infants. A total of 41 preterm infants with PNAC formed the experimental group, and 56 preterm infants receiving total parenteral nutrition (TPN) for >14 days but without cholestasis formed the control group. Genomic DNA was extracted from peripheral venous blood leukocytes. Polymerase chain reaction was used to amplify exon 6 of the MDR3 gene. The target band of MDR3 gene exon 6 was identified in all blood samples from all cases. We identified five cases with C. 504 C>T heterozygous mutations of exon 6 of the MDR3 gene and 14 cases with C. 504 C>T homozygous mutations in the experimental group. In the control group, we identified seven cases with the C. 504 C>T homozygous mutation and six cases with the C. 504 C>T heterozygous mutation. The distribution of the T/C allele frequency of C. 504 in exon 6 of the MDR3 gene between the experimental group and control group was statistically significant (P<0.05). Further analysis revealed the odds ratio of the T/C allele frequency of the C. 504 mutation in exon 6 of the MDR3 gene between the experimental group and control group to be 0.316. Point mutation C. 485 T>A was detected in one case in the experimental group. The C. 504 C>T and C. 485 T>A MDR3 mutations in exon 6 are possibly responsible for the development of PNAC in infants. C. 504 C>T may not be the only risk factor of neonatal PNAC. In order to further confirm the association between exon 6 of the MDR3 gene and PNAC, a large-sample multicenter study should be carried out.