Multiplex sequence-specific polymerase chain reaction reveals new MASP2 haplotypes associated with MASP-2 and MAp19 serum levels

Deficiency of mannan-binding lectin-associated serine protease 2 (MASP-2) has been associated with infections, whereas high levels appear to increase the risk of inflammatory disorders. Nevertheless, MASP2 haplotypes have been poorly investigated. To overcome haplotyping cost and time consumption, we developed multiplex polymerase chain reactions with sequence-specific primers (PCR-SSP) for 8 single nucleotide polymorphisms (SNPs), reducing the number of necessary reactions from 18 to 7. SNPs were distributed from the promoter to the last exon, and a single PCR-SSP was used for p.D120G. We evaluated the phylogenetic relationships and global distribution of 10 identified haplotypes in 338 Danish individuals with known MASP-2 and MAp19 levels and 309 South Brazilians. Four haplotypes were associated with reduced MASP-2 levels in plasma (lower than 200 ng/mL). Simultaneous association with the highest MASP-2 (over 600 ng/mL) and lowest MAp19 levels (lower than 200 ng/mL) was demonstrated with the intron 9 mutation (Kruskal-Wallis p <0.0001). Cumulative genotype frequencies predict approximately 0.4% severely deficient and 25% overproducing individuals in both populations. Rapid and low-cost screening of patients with multiplex MASP2 PCR-SSP could be used to identify clinical conditions where MASP-2 (or MAp19) levels may be disease modifying, possibly improving disease outcome through early therapeutic and preventive measures.