Increased risk of intracranial hemorrhage in preterm infants with OPRM1 gene A118G polymorphism.

Background: To investigate the relationship between the OPRM1 gene A118G polymorphism and intracranial hemorrhage (ICH) in premature infants and identify the relevant genes in disease occurrence.

Methods: In the present case study analysis, polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) was used to detect the genotype and allele frequencies of the OPRM1 gene All8G single nucleotide polymorphism (SNP) in a case group of premature infants with ICH (n=167) and a control group of premature infants (n=163) without ICH.

Results: In the case group, 73 (43.7%) wild type A118 homozygous (A/A), 82 (49.1%) mutant heterozygous (A/G), and 12 (7.2%) mutant G118 homozygous (G/G) individuals were observed. The frequencies of A and G alleles were 68.3% and 31.7% respectively. In the control group, 89 (54.6%) wild type A118 homozygous (A/A), 68 (41.7%) mutant heterozygous (A/G), and 6 (3.7%) mutant G118 homozygous (G/G) individuals were observed. The frequencies of A and G alleles were 75.5% and 24.5% respectively. There was no significant difference in the frequency distribution of the OPRM1 gene A118G polymorphism between the two groups (χ=4.839, P=0.089). There was a significant difference in the positive rate of wild-type AA and mutant-type (A/G + G/G) between the two groups (χ=3.913, P=0.048). Carrying the G allele of the individual was 1.5 times more frequent suffering from the risk of ICH than carrying the A allele [odds ratio (OR): 1.549; 95% confidence interval (CI): 1.003-2.391], indicating that the OPRM1 118G allele was positively correlated with ICH and can increase the risk of ICH occurrence.

Conclusions: The OPRM1 gene A118G polymorphism is associated with ICH in premature infants. The OPRM1 gene A118G may play a critical role in the occurrence of ICH.