A19 SINGLE-NUCLEOTIDE POLYMORPHISMS (SNPS) OF MBL2 GENE OF MANNOSE BINDING LECTIN (MBL) AND MBL SERUM LEVELS AS BIOMARKERS PREDICTIVE OF ADVERSE NEUROLOGICAL OUTCOME IN PRETERM INFANTS

Background: Studies on animal models have shown that MBL-mRNA is expressed in brain tissue and MBL may play a role in the brain dysfunction secondary to ischemia-reperfusion injuries.Serum MBL levels vary widely between individuals, due to the presence, in the exon 1 and in the promoter of the MBL2 gene, of Single-Nucleotide Polymorphisms (SNPs), that influence the expression and the stability of the circulating protein. SNPs of the gene MBL2 and circulating MBL, influencing the activation of the lectin pathway of the complement in the brain tissue, could affect the severity of histopathological lesions of the brain during ischemia-reperfusion events in preterm infants and predict the risk of adverse neurological outcome. Objectives: To evaluate the association between SNPs of the MBL2 gene, MBL serum levels on admission to Neonatal Intensive Care Unit (NICU) and the neurological outcome, assessed during two years follow up, in preterm infants. Methods: 74 infants born at a gestational age = 32 weeks were studied for MBL2 genotype.Genomic DNA was extracted from blood samples, using the QIAmp DNA Blood kit (Qiagen, Hilden, Germany). Exon 1 of the human MBL2 gene (mutant codons 52, 54 and 57) and its promoter region mutations (codons -221 and -550) were genotyped by polymerase chain reaction (PCR) and restriction fragment length polymorphism (PCR-RFLP) assay. For exon 1, the wild type was designated as allele A and mutations ( B as the mutant in codon 54, C in codon 57, and D in codon 52) were pooled and designated as allele 0. For promoter region mutations, the wild type was designated as allele L (position -550) with H as the mutant and allele Y (position -221) with X as the mutant. In a subgroup of 45 infants serum MBL levels had been measured on admission in NICU, using an immunoassay (MBL oligomer ELISA, Antibody Shop, Copenhagen, Denmark). 0,75 μg/ml was the cut-off to discriminate MBL deficiency. Children were subsequently evaluated by clinical exams, brain imaging, auditory brainstem response, eyes examinations during a two years follow up. All children received the Bayley II scales of infant development at 12 and 24 months of corrected age. The adverse neurological outcome was defined as a Mental Development Index Score = 70 at the Bayley II scales at 24 months of corrected age , associated with one or more sensory or motor severe deficits. Results: 5/5 (100,0%) children with SNPs of the exon 1 showed an adverse neurological outcome, compared to 27/69 (39,1%) children wild type (p=0,01). We find no associations with SNPs of the promoter region. The risk of an adverse neurological outcome was higher, but not significantly, in infants with low MBL serum levels on admission than in infants with MBL above the cut-off (38,9 versus 25,0; OR 1,91; p=0,3). Conclusions: SNPs of the exon 1 of the MBL2 gene, seem to be associated with a worse neurological outcome in preterm infants and may be predictive of increased neurological risks.