Objective This cross-sectional study was aimed at determining the allele frequencies for the CYP2C19*2, CYP2C19*3, CYP2D6*10 and PON1 (rs662) polymorphisms in the Puerto Rican population. The CYP2C19, CYP2D6 and PON1 genes are known to be associated with functional changes in drug metabolism and activation. Individuals carrying the aforementioned polymorphisms are at a higher risk of suffering from drug-induced adverse events and/ or unresponsiveness from a variety of drugs that includes antidepressants, atypical antipsychotics and antiplatelet compounds. Information on the frequency of these polymorphisms is more commonly found on homogeneous populations, but is scarce in highly heterogeneous populations like Hispanics, as in the case of Puerto Ricans. Method Genotyping was carried out in 100 genomic DNA samples from dried blood spots supplied by the Puerto Rican Newborn Screening program using Taqman® Genotyping Assays. Results The Minor Allele Frequencies (MAF) obtained were 9% for CYP2C19*2 and CYP2D6*10, 50% for PON1 (rs662), while the CYP2C19*3 variant was not detected in our study. Furthermore, Hardy Weinberg equilibrium analysis was assessed as well as a comparison between Puerto Rico and other reference populations using a Z-test for proportions. Conclusion The observed allele and genotype frequencies on these relevant pharmacogenes in Puerto Ricans were more closely related to those early reported in two other reference populations of Americans (Mexicans and Colombians).

Puerto Ricans are a unique Hispanic population with European, Native American (Taino), and higher West African ancestral contributions than other non-Caribbean Hispanics. In admixed populations, such as Puerto Ricans, genetic variants can be found at different frequencies when compared to parental populations and uniquely combined and distributed. Therefore, in this review, we aimed to collect data from studies conducted in healthy Puerto Ricans and to report the frequencies of genetic polymorphisms with major relevance in drug response. Filtering for healthy volunteers or individuals, we performed a search of pharmacogenetic studies in academic literature databases without limiting the period of the results. The search was limited to Puerto Ricans living in the island, excluding those studies performed in mainland (United States). We found that the genetic markers impacting pharmacological therapy in the areas of cardiovascular, oncology, and neurology are the most frequently investigated. Coincidently, the top causes of mortality in the island are cardiovascular diseases, cancer, diabetes, Alzheimer’s disease, and stroke. In addition, polymorphisms in genes that encode for members of the CYP450 family (CYP2C9, CYP2C19, and CYP2D6) are also available due to their relevance in the metabolism of drugs. The complex genetic background of Puerto Ricans is responsible for the divergence in the reported allele frequencies when compared to parental populations (Africans, East Asians, and Europeans). The importance of reporting the findings of pharmacogenetic studies conducted in Puerto Ricans is to identify genetic variants with potential utility among this genetically complex population and eventually move forward the adoption of personalized medicine in the island.

Warfarin is an oral anticoagulant that requires individual monitoring since serious adverse events are common. CYP2C9 encodes for the enzyme mainly responsible of S‐warfarin’s metabolism. Polymorphisms in CYP2C9 have been previously found to be strongly associated with observed warfarin dose variability in different populations, but not in Caribbean Hispanics. Caribbean Hispanics originated as a result of a complex admixture among Caucasians, Africans and Amerindians ancestors‐a characteristic that should be considered for warfarin management. The rare loss‐of‐function CYP2C9*8 allelic variant is reportedly more prevalent among individuals with African heritage. Since Puerto Ricans has a significant contribution of African ancestry in their genetic backgrounds, this cross‐sectional study was aimed to determine the frequency of CYP2C9*8 in a cohort of 150 Puerto Rican patients undergoing warfarin therapy. DNA specimens were extracted and genotyped for the CYP2C9*8 using a PCR‐based Taqman genotyping assay. We found 3 heterozygous for the CYP2C9*8 variant in our study cohort, corresponding to a minor allele frequency of 1% (95%CI: 0.0026‐0.031). The observed frequency met Hardy‐Weinberg equilibrium. Allele frequency in our cohort was found to be significantly lower than that from a previous report in African‐Americans (0.01 versus 0.047, respectively, p=0.045 by two‐tailed z‐test), with a carrier frequency of 1 in 50 (Puerto Ricans) versus 1 in 11 (African‐Americans). Due to the CYP2C9*8 prevalence found among Puerto Ricans, we concluded that this variant should be included in any pharmacogenetic‐guided algorithm for warfarin dose predictions in this population. Approved by University of Puerto Rico, Medical Sciences Campus Institutional Review Board protocol A4070109. Grant Funding Source: Supported by NIH grants# 5SC2HL110393 (NHLBI) and grant# G12RR‐03051 (RCMI‐ NCRR).

TWIST2 is a transcription factor of the basic Helix Loop Helix family, which binds DNA as homo or heterodimer to consensus sequences called E ‐ boxes. Mutations in TWIST2 cause a rare recessive disorder called Setleis Syndrome. To this date, no structural or functional assays have been published using recombinant TWIST2. First, we performed a bioinformatics analysis ranging from multiple sequence alignments to key structural features. These led us to perform a 3D structural prediction of TWIST2 using the Phyre2 server. In order to produce recombinant His tagged TWIST2, the TWIST2 cDNA was cloned into the pQET7 vector and expressed in BL21 pLysS cells. The protein was purified under native conditions by a two‐step purification via Ni‐NTA Affinity followed by Ion Exchange Chromatography. After purification, a band of the expected size of TWIST2 was observed in SDS‐PAGE. Western Blot analysis and Mass Spectrometry validated this finding. TWIST2 functionality was demonstrated by Electrophoretic Mobility Shift Assay (EMSA) with a known E‐box probe. Obtaining recombinant TWIST2 protein will allow future structural and functional assays. These assays will expand the knowledge of this transcription factor and its interactions with DNA to regulate its target genes. Grant Funding Source: Supported by NIH grants (2G12‐RR003051), (8G12‐MD007600) and (R25GM061838)