METHODS: Demographic, clinical and genotype data were determined for 1122 women (267 cases and 855 controls) recruited from the University of Malaya Medical Centre in the Klang Valley, Kuala Lumpur. Relevant articles were identified from Pubmed, Embase, MEDLINE, and Web of Science. Extraction of data was carried out and summary estimates of the association between rs780094 and GDM were examined.
RESULTS: The frequency of risk allele C was significantly higher in the cases than controls (OR 1.34, 95% CI 1.09-1.66, P = 0.006). The C allele was also associated with increased level of random 2-hour fasting plasma glucose and pregravid body mass index. Meta-analysis further confirmed the association of the GCKR rs780094 with GDM (OR 1.32, 95% CI 1.14-1.52, P = 0.0001).
CONCLUSION: This study strongly suggests that GCKR rs780094-C is associated with increased risk of GDM.
METHODS: A total of 36 full-length pkmsp1p sequences along with the reference H-strain and 40 C-terminal pkmsp1p sequences from clinical isolates of Malaysia were downloaded from published genomes. Genetic diversity, polymorphism, haplotype and natural selection were determined using DnaSP 5.10 and MEGA 5.0 software. Genealogical relationships were determined using haplotype network tree in NETWORK software v5.0. Population genetic differentiation index (F ST ) and population structure of parasite was determined using Arlequin v3.5 and STRUCTURE v2.3.4 software.
RESULTS: Comparison of 36 full-length pkmsp1p sequences along with the H-strain identified 339 SNPs (175 non-synonymous and 164 synonymous substitutions). The nucleotide diversity across the full-length gene was low compared to its ortholog pvmsp1p. The nucleotide diversity was higher toward the N-terminal domains (pkmsp1p-83 and 30) compared to the C-terminal domains (pkmsp1p-38, 33 and 19). Phylogenetic analysis of full-length genes identified 2 distinct clusters of P. knowlesi from Malaysian Borneo. The 40 pkmsp1p-19 sequences showed low polymorphisms with 16 polymorphisms leading to 18 haplotypes. In total there were 10 synonymous and 6 non-synonymous substitutions and 12 cysteine residues were intact within the two EGF domains. Evidence of strong purifying selection was observed within the full-length sequences as well in all the domains. Shared haplotypes of 40 pkmsp1p-19 were identified within Malaysian Borneo haplotypes.
CONCLUSIONS: This study is the first to report on the genetic diversity and natural selection of pkmsp1p. A low level of genetic diversity and strong evidence of negative selection was detected and observed in all the domains of pkmsp1p of P. knowlesi indicating functional constrains. Shared haplotypes were identified within pkmsp1p-19 highlighting further evaluation using larger number of clinical samples from Malaysia.