Mannose binding lectin (mbl2) haplotype frequencies in solid organ transplant patients and correlation with MBL protein levels--evaluation of complement-mediated effector pathway deficiency.

Mannose-binding lectin (MBL) is a protein critical in activating complement. Patients with wild-type and variant mbl2 genotypes have high or low concentrations of MBL protein, which is known to increase susceptibility to transplant rejection or infection, respectively. Our objective was to determine mbl2 genotype frequencies in future solid organ transplant recipients in order to optimize their induction and maintenance immunosuppressive therapies, and to provide MBL reference data for this unique population. We genotyped 1687 patients, and concurrently measured protein in 807 of them, during 2010-2011. Frequencies of the structural allele SNPs in our population were similar to those of other studied populations; however, Black patients with the same intermediate and deficient mbl2 genotypes as Caucasians produced significantly lower levels of MBL protein; therefore, within this population more genotypes should be considered MBL-deficient. Overall, the most critical parameter in determining serum MBL protein concentration was genotype, which was independent of other factors including ethnicity, gender, or diseased native organ type.