Integrated surveillance strategy to support the prevention of neural tube defects through food fortification with folic acid: the experience of Costa Rica.

PURPOSE: (1) To describe how Costa Rica implemented an integrated surveillance strategy of folate deficiency, neural tube defects (NTDs) prevalence, NTDs-associated infant mortality rate (NTDs-IMR), and folic acid food fortification (FAFF), to support with evidence NTDs prevention policies; (2) to disseminate updated data from monitoring programs. METHODS: We performed a cross-sectional analysis, using the databases of national surveillance systems for NTDs outcomes to compare NTDs-prevalence and NTDs-IMR observed in the pre-fortification (1987-1998) and post-fortification (2010-2020) periods. In addition, using data from FAFF monitoring program (2010-2020), means of folic acid concentration (mg/kg) and folic acid daily intake (µg/day) were calculated for each fortified food (corn and wheat flour, rice and milk), as well as its contribution to folic acid estimated average requirement (EAR). RESULTS: After FAFF Costa Rica showed a decrease of 84% in folic acid deficiency in women of childbearing age, as well as a 53% decrease in the prevalence of NTDs, falling from 11.82/10,000 to 5.52/10,000 livebirths. In addition, there was a 76% reduction in the NTDs-IMR from 77.01/100,000 to 18.66/100,000 livebirths. Between 2010 and 2020, all fortified foods provided an average contribution of 119% of the EAR of folic acid in the population. CONCLUSION: To reduce NTD risk, an integrated surveillance strategy is essential not only to base prevention strategies on evidence, but also to demonstrate their impact and improve interventions over time. The experience in Costa Rica provides evidence that this type of surveillance is feasible to be implemented in developing countries.

A CRISPR/Cas9-based method and primer design tool for seamless genome editing in fission yeast.

In the fission yeast Schizosaccharomyces pombe the prevailing approach for gene manipulations is based on homologous recombination of a PCR product that contains genomic target sequences and a selectable marker. The CRISPR/Cas9 system has recently been implemented in fission yeast, which allows for seamless genome editing without integration of a selection marker or leaving any other genomic 'scars'. The published method involves manual design of the single guide RNA (sgRNA), and digestion of a large plasmid with a problematic restriction enzyme to clone the sgRNA. To increase the efficiency of this approach, we have established and optimized a PCR-based system to clone the sgRNA without restriction enzymes into a plasmid with a dominant natMX6 (nourseothricin) selection marker. We also provide a web-tool, CRISPR4P, to support the design of the sgRNAs and the primers required for the entire process of seamless DNA deletion. Moreover, we report the preparation of G1-synchronized and cryopreserved S. pombe cells, which greatly increases the efficiency and speed for transformations, and may also facilitate standard gene manipulations. Applying this optimized CRISPR/Cas9-based approach, we have successfully deleted over 80 different non-coding RNA genes, which are generally lowly expressed, and have inserted 7 point mutations in 4 different genomic regions.