Phenyl Thiocarbanate and Polymerase Chain Reaction - Research Paper Example

PTC GENOTYPE PRACTICAL School Phenylthiocarbamide (PTC) also known as phenylthiorea (PTU) is an organosulfur thiorea that has phenyl ring (Karlsson, Et al., 2001). This chemical has a unique characteristic in that it tastes very bitter to some people or has no taste to other people (Woodings, 2012). PTC tasting is a genetically controlled ability to taste PTC and related substances, these have antithyroid activity (F.D. Kitchin, 1959). The PTC tasting ability is governed by a pair of alleles, dominant T for tasting and recessive t for non-tasting. People who have genotypes TT and Tt are tasters while those with genotype tt are non tasters. PTC tasting is determined by the level of dithiotyrosine in the saliva and this may be correlated to the dislike of plants in the Brassica genus among some people (M. Padmavathi, 2013). PTC is not found naturally, however, the ability to taste PTC correlates with the ability to taste other bitter substances that are found naturally. The PTC gene explains 85% of the total influence on whether a person is a taster or a non-taster, other factors such as having a dry mouth, explain the remaining 15% (HHMI, 2015). This explains why some people find some food too bitter to taste while other find this food not bitter at all. Introduction PTC has a unique characteristic because it tastes bitter to some people and has no taste to others. . PTC tasting is a genetically controlled ability to taste PTC and related substances that have antithyroid activity. Genotype refers to the genetic makeup or composition of an organism. Alleles is alternative forms of similar gene that occupy the same location in the chromosome. There are two alleles at any given locus; one on each chromosome in the pair. One is from the mother and the other is from the father.(USA National Library of Medicine, 2015) The PTC tasting ability is governed by a pair of alleles, dominant T for tasting and recessive t for non-tasting. People who have genotypes TT and Tt are tasters while those with genotype tt are non tasters. If the alleles are TT or tt, the genotype is homozygous. If the alleles are different such as Tt, the genotype is heterozygous (M. Fareed, 2012). It is rare that one gene determines only one characteristic as in the case for PTC tasting, this is a monogenetic trait. Most genes are complex and have traits that affect more than one locus they are polygenic. PTC tasting is determined by the level of dithiotyrosine in the saliva (F.D. Kitchin, 1959). Although PTC tasting correlates with the ability to taste bitter naturally occurring substances. Tasters vary greatly in their sensitivity to PTC. Although the PTC gene explains 85% of a person’s ability to taste, other factors such as having a dry mouth explain the remaining 15% (HHMI, 2015). Phenotype refers to an organism’s observable behavior, these are usually the expression of a gene or the clinical representation of a particular genotype in the individual (ghr, 2015). The phenotype is influenced throughout a person’s development by environmental factors such as diet, climate, stress and illness. The extent to which a person’s phenotype is determined by his genotype is called phenotypic plasticity (DW. Whiteman). The interaction between genetics and environment are what make each individual unique. The difference to taste PTC among various people has been mapped to chromosome 7q and is directly related to TAS2R38 genotype (Drayna D. Et al., 2003). There are three common polymorphisms in the TAS2R38 GENE-A49P, V262A and I296V that combine to form haplotypes with the common been AVI-non taster and PAV-taster (D.S. Skuse, 2014). The varying combinations of these haplotypes yield homozygotes PAV/PAV and AVI/AVI and heterozygotes for PAV/AVI. People possessing two copies of PAV polymorphism (PAV homozygous) report PTC as very bitter while those with two copies of AVI (AVI homozygous) report PTC been tasteless (Woodings,2012). This polymorphism affects taste by altering the G-protein binding domains (Robert Fredriksson, 2003). TAS2R38 utilizes the G-protein gustducin as the primary mechanism of signal transduction. TAS2R38 is also sensitive to the bitter compound 6-n-propylthiouracil (PROP) (Margolskee RF, 2001). It has been seen that some heterozygotes may become PROP supertasters despite not having two PAV alleles indicating an overlap between the PROP bitterness levels and varying TAS2R38 genotypes. Therefore, mechanisms beyond the TAS2R38 genotype contribute to super tasting capabilities (Hayes et al., 2007). Methods and Materials Phenyl Thiocarbanate (PTC) Polymerase chain reaction (PCR) based genetic analysis of the PTC genotype using human-specific DNA primers In order to isolate the genomic DNA, a sterile wooden splint was used to scrap the inside of the cheeks to remove loose buccal (cheek) cells. The sterile wooden splint was put into a test tube containing 10ml water. The tube was centrifuge at 3000rpm for 3 minutes and the supernatant carefully poured off so as to retain the cell pellets. A 350 μl 5% Chelex suspension was added so as to suspend pellet buccal cells, all contents were then transferred to a new 1.5 ml eppendorf tube.4 μl of Proteinase K (Stock solution; 10mg/ml) was added to eppendorf containing buccal cells and Chelex. The solution was then incubated at 56˚C for 30 minutes and the tube was shook briefly for 10 seconds. The tube was then centrifuge at maximum of13, 000 rpm for 20 seconds while ensuring centrifuge is balanced. The tube containing Chelex/cells is then placed in a water bath/heating block at 98˚C for 15 min. The tube was shook for 10 seconds and then centrifuge tube at maximum speed for 3 min. The supernatant (liquid above the chelex), containing buccal cell DNA (Template) was transfered to a sterile 1.5 ml Eppendorf tube. An aliquot (5 µl) of the sample was taken. The aliquot was measured using the nanodrop nucleic acid measurement machine. Concentration of (ng/µl; A260, A280, 260/280, 260/230) were retained for reference. The DNA concentrations of taste perception phenotype (ST/MT/NT) were recorded in excel spread sheet. Polymerase Chain Reaction Set up The micro-eppendorf tube was used to assemble the PCR reaction. The master mix had all the PCR reaction components permitting detection of PTC gene. However, it did not contain the template DNA.43.5l Master mix (already prepared) and 6.5l Template DNA prep. (Buccal cell DNA) (Total volume = 50l) was put in one tube and mixed so that the solution contents settled at the bottom of the tube. The procedure was mixing the solutions to dissolve (flicking with a finger) and then the tube was pulse spun to gather the liquid contents to the bottom of the tube. The tube was then placed in a template for thermal cycler, the lid was held firmly. The used position of the tube was marked. The following program for the experiment was used: 94˚C 4 minutes 55˚C 40 seconds 72˚C 40 seconds 40 cycles 94˚C 40 seconds 55˚C 5 minutes 72˚C 5 minutes The reaction tubes were then stored at -200C after the completion of all the cycles. Biomolecular Techniques RFLP Protocol prior to Gel Electrophoresis The PCR tube was retrieved and an aliquot (20 µl)removed and added to a 0.5 ml eppendorf tube containing 10 µl of Fnu4HI restriction enzyme master. The solution was held firmly without shaking. The solution was then mixed by flicking with finger, then centrifuge briefly and place in 37°C heating block. A unique mark on was put in the tube and heating block template where your Fnu4HI digested PCR tube was located. The PCR tube was then returned to its position in the container and left for two hours as the Fnu4HI restriction enzyme digest acted on the solution. A setup composed of 2% submerged agarose gel; Geneflow tanks (PurpleLids, 12 well comb) 70 ml, Peqlab / Hybaid tanks (10 well comb) 50ml agarose was prepared and left to set. A 3 µl of DNA loading buffer (x5) was added to a tube containing 12 µl PCR/R Enzyme digest (morning). A 3 µl of DNA loading buffer (x5) was also added to a tube containing 12 µl residual PCR. The solution in the two tubes was then mixed and spun a 10 µl of this mixture was added to a 2% agarose gel submerged in TBE buffer. A 10 µl of 100 bp DNA Ladder was added to the remaining well as a DNA marker. The solution was taken through electrophoresis at 90 V for 45min until blue marker was formed halfway through the gel. The gel was photographed under UV transillumination. The Ethidium Bromide &Agarose gel was safely disposed in the biological waste bin. DNA primer pairs; PTC Forward 1 AACTGGCAGAATAAAGATCTCAATTTAT PTC Reverse 2 AACACAAACCATCACCCCTATTTT Results LOCUS AY258597 1002 bp DNA linear PRI 29-APR-2003 DEFINITION Homo sapiens PTC bitter taste receptor (PTC) gene, PTC-taster allele, complete cds. ACCESSION AY258597 VERSION AY258597.1 GI:30230488 KEYWORDS . SOURCE Homo sapiens (human) ORGANISM Homo sapiens Eukaryota; Metazoa; Chordata; Craniata; Vertebrata; Euteleostomi; Mammalia; Eutheria; Euarchontoglires; Primates; Haplorrhini; Catarrhini; Hominidae; Homo. REFERENCE 1 (bases 1 to 1002) AUTHORS Kim,U.K., Jorgenson,E., Coon,H., Leppert,M., Risch,N. and Drayna,D. TITLE Positional cloning of the human quantitative trait locus underlying taste sensitivity to phenylthiocarbamide JOURNAL Science 299 (5610), 1221-1225 (2003) PUBMED 12595690 REFERENCE 2 (bases 1 to 1002) AUTHORS Kim,U.-K. and Drayna,D.T. TITLE Direct Submission JOURNAL Submitted (17-MAR-2003) NIDCD, NIH, 5 Research Court, Rockville, MD 20850, USA FEATURES Location/Qualifiers source 1..1002 /organism="Homo sapiens" /mol_type="genomic DNA" /db_xref="taxon:9606" /chromosome="7" /map="7q35-q36" gene 1002 /gene="PTC" /allele="taster" mRNA 1002 /gene="PTC" /allele="taster" /product="PTC bitter taste receptor" CDS 1..1002 /gene="PTC" /allele="taster" /note="7 transmembrane G protein coupled receptor" /codon_start=1 /product="PTC bitter taste receptor" /protein_id="AAP14666.1" /db_xref="GI:30230489" /translation="MLTLTRIRTVSYEVRSTFLFISVLEFAVGFLTNAFVFLVNFWDV VKRQPLSNSDCVLLCLSISRLFLHGLLFLSAIQLTHFQKLSEPLNHSYQAIIMLWMIA NQANLWLAACLSLLYCSKLIRFSHTFLICLASWVSRKISQMLLGIILCSCICTVLCVW CFFSRPHFTVTTVLFMNNNTRLNWQIKDLNLFYSFLFCYLWSVPPFLLFLVSSGMLTV SLGRHMRTMKVYTRNSRDPSLEAHIKALKSLVSFFCFFVISSCAAFISVPLLILWRDK IGVMVCVGIMAACPSGHAAVLISGNAKLRRAVMTILLWAQSSLKVRADHKADSRTLC" variation 145 /gene="PTC" /note="compared to TAS2R38 sequence found in GenBank Accession Number AF494231; results in proline to alanine amino acid change" /replace="g" variation 557 /gene="PTC" /note="compared to TAS2R38 sequence found in GenBank Accession Number AF494231; results in isoleucine to asparagine amino acid change" /replace="a" variation 785 /gene="PTC" /note="compared to TAS2R38 sequence found in GenBank Accession Number AF494231; results in alanine to valine amino acid change" /replace="t" variation 886 /gene="PTC" /note="compared to TAS2R38 sequence found in GenBank Accession Number AF494231; results in valine to isoleucine amino acid change" /replace="a" ORIGIN 1 atgttgactc taactcgcat ccgcactgtg tcctatgaag tcaggagtac atttctgttc 61 atttcagtcc tggagtttgc agtggggttt ctgaccaatg ccttcgtttt cttggtgaat 121 ttttgggatg tagtgaagag gcagccactg agcaacagtg attgtgtgct gctgtgtctc 181 agcatcagcc ggcttttcct gcatggactg ctgttcctga gtgctatcca gcttacccac 241 ttccagaagt tgagtgaacc actgaaccac agctaccaag ccatcatcat gctatggatg 301 attgcaaacc aagccaacct ctggcttgct gcctgcctca gcctgcttta ctgctccaag 361 ctcatccgtt tctctcacac cttcctgatc tgcttggcaa gctgggtctc caggaagatc 421 tcccagatgc tcctgggtat tattctttgc tcctgcatct gcactgtcct ctgtgtttgg 481 tgctttttta gcagacctca cttcacagtc acaactgtgc tattcatgaa taacaataca 541 aggctcaact ggcagattaa agatctcaat ttattttatt cctttctctt ctgctatctg 601 tggtctgtgc ctcctttcct attgtttctg gtttcttctg ggatgctgac tgtctccctg 661 ggaaggcaca tgaggacaat gaaggtctat accagaaact ctcgtgaccc cagcctggag 721 gcccacatta aagccctcaa gtctcttgtc tcctttttct gcttctttgt gatatcatcc 781 tgtgctgcct tcatctctgt gcccctactg attctgtggc gcgacaaaat aggggtgatg 841 gtttgtgttg ggataatggc agcttgtccc tctgggcatg cagccgtcct gatctcaggc 901 aatgccaagt tgaggagagc tgtgatgacc attctgctct gggctcagag cagcctgaag 961 gtaagagccg accacaaggc agattcccgg acactgtgct ga // Fig.2. Representative Graph plotted from the data obtained from the Log (MWT) against distance travelled by the ladder fragments (data are on table). Calculation: From the graph the equation is y = -0.0458x + 3.5083 In which Y= Molecular Weight fragment, X= Travelled Distance Unknown undigested DNA y = -0.0458x + 3.5083 y = -0.0458(23) + 3.5083 y = -1.0534 + 3.5083 y = 2.4549 y = anti log 2.4549 y= 285.036 Unknown Digested DNA y = -0.0458x + 3.5083 y = -0.0458(25) + 3.5083 y = -1.145+ 3.5083 y = 2.3633 y = anti log 2.3633 y= 230.834 Non taster: LOCUS AY258598 1002 bp DNA linear PRI 29-APR-2003 DEFINITION Homo sapiens PTC bitter taste receptor (PTC) gene, PTC-non-taster allele, complete cds. ACCESSION AY258598 VERSION AY258598.1 GI:30230490 1 atgttgactctaactcgcatccgcactgtgtcctatgaagtcaggagtacatttctgttc 61 atttcagtcctggagtttgcagtggggtttctgaccaatgccttcgttttcttggtgaat 121 ttttgggatgtagtgaagaggcaggcactgagcaacagtgattgtgtgctgctgtgtctc 181 agcatcagccggcttttcctgcatggactgctgttcctgagtgctatccagcttacccac 241 ttccagaagttgagtgaaccactgaaccacagctaccaagccatcatcatgctatggatg 301 attgcaaaccaagccaacctctggcttgctgcctgcctcagcctgctttactgctccaag 361 ctcatccgtttctctcacaccttcctgatctgcttggcaagctgggtctccaggaagatc 421 tcccagatgctcctgggtattattctttgctcctgcatctgcactgtcctctgtgtttgg 481 tgcttttttagcagacctcacttcacagtcacaactgtgctattcatgaataacaataca 541 aggctcaactggcagattaaagatctcaatttattttattcctttctcttctgctatctg 601 tggtctgtgcctcctttcctattgtttctggtttcttctgggatgctgactgtctccctg 661 ggaaggcacatgaggacaatgaaggtctataccagaaactctcgtgaccccagcctggag 721 gcccacattaaagccctcaagtctcttgtctcctttttctgcttctttgtgatatcatcc 781 tgtgttgccttcatctctgtgcccctactgattctgtggcgcgacaaaataggggtgatg 841 gtttgtgttgggataatggcagcttgtccctctgggcatgcagccatcctgatctcaggc 901 aatgccaagttgaggagagctgtgatgaccattctgctctgggctcagagcagcctgaag 961 gtaagagccgaccacaaggcagattcccggacactgtgctga Red= SNP Yellow= Forward Primer Green= Reverse primer Taster: LOCUS AY258597 1002 bp DNA linear PRI 29-APR-2003 DEFINITION Homo sapiens PTC bitter taste receptor (PTC) gene, PTC-taster allele, complete cds. ACCESSION AY258597 VERSION AY258597.1 GI:30230488 1 atgttgactctaactcgcatccgcactgtgtcctatgaagtcaggagtacatttctgttc 61 atttcagtcctggagtttgcagtggggtttctgaccaatgccttcgttttcttggtgaat 121 ttttgggatgtagtgaagaggcagccactgagcaacagtgattgtgtgctgctgtgtctc 181 agcatcagccggcttttcctgcatggactgctgttcctgagtgctatccagcttacccac 241 ttccagaagttgagtgaaccactgaaccacagctaccaagccatcatcatgctatggatg 301 attgcaaaccaagccaacctctggcttgctgcctgcctcagcctgctttactgctccaag 361 ctcatccgtttctctcacaccttcctgatctgcttggcaagctgggtctccaggaagatc 421 tcccagatgctcctgggtattattctttgctcctgcatctgcactgtcctctgtgtttgg 481 tgcttttttagcagacctcacttcacagtcacaactgtgctattcatgaataacaataca 541 aggctcaactggcagattaaagatctcaatttattttattcctttctcttctgctatctg 601 tggtctgtgcctcctttcctattgtttctggtttcttctgggatgctgactgtctccctg 661 ggaaggcacatgaggacaatgaaggtctataccagaaactctcgtgaccccagcctggag 721 gcccacattaaagccctcaagtctcttgtctcctttttctgcttctttgtgatatcatcc 781 tgtgctgccttcatctctgtgcccctactgattctgtggcgcgacaaaataggggtgatg 841 gtttgtgttgggataatggcagcttgtccctctgggcatgcagccgtcctgatctcaggc 901 aatgccaagttgaggagagctgtgatgaccattctgctctgggctcagagcagcctgaag 961 gtaagagccgaccacaaggcagattcccggacactgtgctga Table 1: the percentage and the frequency of 108 students who are either a homozygous or heterozygous Table 2: Allele frequency of student’s class Allele type C T Number (216) 93 123 Allele frequency 0.430 (43%) 0.569 (57%) Table 3 the percentage and the frequency of 226 persons who are either a homozygous or heterozygous (European cohort) Genotype taster genotype (CC) mild tasters (CT) non tasters (TT) Number of persons 44 106 76 Frequency 0.195 0.469 0.336 Frequency as percentage 20 50 30 Table 4: Allele frequency of European people Allele type T C Number (452) 258 194 Allele frequency 0.571 0.429 Table 5 shows the percentage and the frequency of 224 persons who are either a homozygous or heterozygous (sub-Sahara cohort) Table 6: Allele frequency of sub-Sahara people Allele type C T Number (448) 306 142 Allele frequency 0.683 (68.3%) 0.317 (31.7%) Chi Square from Mini tab: Student Vs European Rows: Worksheet rows Columns: Worksheet columns C785 T785 All 1 93 123 216 92.8 123.2 2 194 258 452 194.2 257.8 All 287 381 668 Cell Contents: Count Expected count Pearson Chi-Square = 0.001; DF = 1; P-Value = 0.974 Likelihood Ratio Chi-Square = 0.001; DF = 1; P-Value = 0.974 The class data was found to be similar to other European data that calculated the P-value to be 0.05 (p>0.05). Student Vs Sub Saharaian Africa Rows: Worksheet rows Columns: Worksheet columns C785 T785 All 1 93 123 216 129.8 86.2 2 306 142 448 269.2 178.8 All 399 265 664 Cell Contents: Count Expected count Pearson Chi-Square = 38.738; DF = 1; P-Value = 0.000 Likelihood Ratio Chi-Square = 38.405; DF = 1; P-Value = 0.000 Discussions We used various PCR-based methods to detect specific polymorphisms without sequencing. Detecting polymorphism We detected the sequence differences at the first and middle positions to distinguish PAV tasters, AAV tasters and AVI non tasters by using restriction enzyme that overlaps these two regions and cuts the DNA depending on the allele. There was PCR amplification of 1067bp fragment of the N-terminal portion of TAS2R38. The PCR product was cut with Fnu4H that cut the DNA at the sequence GCNGC (N is A, G, C or T) (Jen Sheng Pei, 2015). This sequence overlaps both sides of polymorphisms. At the amino acid position 262, both the PAV and AAV taster contained the cut site (GCTGC) while AVI non taster did not have (GTTGC). It was possible to discriminate the two tasters’ alleles at amino acid 49 position (Santaok Gill et al. 2007). PAV tasters contained the Fnu4H cut site (GCAGC) while AVI non-tasters and AAV tasters did not (GCAGG). Therefore, the restriction pattern of the 1Kb TAS2R38PCR products indicated the sequence at both polymorphic sites. A 557 Fnu4H fragment in non-tasters was cleaved to 456bp and 75bp fragments in both PAV and AAV tasters. A 336bp Fnu4H fragment in non-tasters or AAV taster was cleaved to 336bp and 27 bp fragment in PAV tasters. Heterozygosis displayed both the cleaved and uncleaved products. The simple phenotype of tasting may be modified by other genetic traits. Super tasters had increased taste bud (fungiform papillae) density and have enhanced taste from multiple taste receptors. Moreover, people may lose taste sensitivity from other genetic and environmental factors. PCR Primers (termini of above 1067 bp PCR product): For:5’CATCCCTCTAAGTTTCCTGCCAGA Rev:5’TTGGGATAATGGCAGCTTGTCCCTC Annealing at 58oC The ability to taste PTC is present in some people and absent in other people. This is due to polymorphism in TS2R38 (PTC) taste receptor gene. From the laboratory experiment we investigated the relationship between the phenotypes as tasters, and non tasters and that of the genotypes as homozygotes (TT or tt) or heterozygotes (Tt).The PTC taste allele is a dominant allele. From the experiment, I was not able to taste the bitter taste of PTC,this indicated I was a homozygous nontaster(tt). The presence of atleast one dominant allele would enable me to taste the PTC such as (Tt) or (TT). My DNA was extracted so as to determine my genotype. The DNA was extract was digested by recognition enzyme and was analyzed through electrophoretic separation of digested and undigested PTC receptor genes. The electrophoretic gel produced a clear image to conclusively determine my genotype- the bands of the digested products were bold and clear. Some distinguishable band of 303bp was observed indicating that I was homozygous recessive (tt) and therefore non taster. The presence of a single band at 303bp for the digested product shows that the restrictive agent Fnu4H1 failed to cut the 303bp PTC gene fragment due to the lack of the restriction recognition site at nucleotide position 785. At this position C is replaced by T on either allele (tt). Therefore, both the phenotype and genotype were similar to expected trend. The other three lanes associated with the undigested products produced bands at 303bp long and were not cut. This indicates that these bands served as controls. PTC is not a natural occurring organic compound; it is a compound that contains isthiocyanate (W. Jimenez, 1999). Naturally, there are a lot of edible vegetables, fruits and trees that contain this compound. These include cabbages, broccoli, Brussels and sprouts. Naturally, most of the bitter compounds are harmful to a person’s health. PTC receptors therefore act as a defense mechanism against toxins (Wooding, et al., 2006). Studies are yet to explain and identify why some heterozygotes (Tt) or persons with recessive gene as homozygotes (tt) may at times become expert tasters. It is believed that these people may have ability to taste certain rare tastes (HHMI, 2015). The bitter tasting perception such as the taste of PTC is a genetic trait governed by TAS2R38 gene. TAS2R38 gene has a great influence in the diet and phenotype of people. According to the experiment, most of the class population was found to be tasters. This data was similar to the results of other European data that suggest that most Europeans are tasters having inherited at least one copy of the PAV gene (Tt) or (TT). The study therefore implies that there are more tasters in the world than non tasters. This study supports other research data that imply that most of the world population is tasters. The experiment found that individuals who were tasters’ homozygote (PAV/PAV) were more sensitive to PTC than heterozygote (PAV/AVI) and the non tasters’ homozygote (AVI/AVI). The presence of these alleles has been observed to influence the dietary behavior of individuals (Wooding et al, 2010). This is through the alteration of the perceived taste quality of food. Individuals who have high taste sensitivity were found to dislike fruits and vegetables. Further studies have also suggested that there is a relationship between TAS2R38 genotype and body mass index (BMI) (H. Inoue, 2013). Moreover excessive consumption of alcohol and smoking has also been associated with TAS2R38 genotype. Studies indicate that individuals who are strong tasters are less likely to become smokers (VB. Duffy, 2004). This indicates that tasters are more likely to find cigarette to be bitter hence less likely to smoke (HHMI, 2015). The bitter taste of some foods might discourage tasters from consuming those foods. Diet rich in phenol, flavonoids and glucosinolates are effective in lowering the risk of cancer and cardiovascular disease (Drewnowski, 2000). The dietary phytoureins found in vegetables and fruits are useful anti-oxidants and anti-tumors (CropPharms, 2015). However, these foods are bitter especially to tasters who may avoid consumption of vegetables rich in these anti-tumor and anti-oxidant compounds and instead consume sweet and fatty foods that could possibly lead to increased risk of cancer and cardiovascular diseases. A similar argument has been presented implying that non tasters might be at risk of lifestyle diseases due to dietary. Non tasters are susceptible to heavy drinking and smoking due to their inability to taste bitter taste (Goldstein et al, 2005). They are also susceptible to consumption of fatty foods (Shivaprasad et al, 2012). This kind of dietary would expose these individuals to diseases such as cancer and obesity. It has also been suggested that non tasters might have a high rate of getting goiter. Goiter is associated with lack of iodine. Non tasters are less sensitive to PTC and related compounds and may therefore consume more compounds with greater quantities of goitrogens found in vegetables (Woodings S. 2006). The inability to taste has also been associated with a number of neurological illnesses not ordinarily related to taste. In an experiment conducted on 67 schizophrenia patients, 30 healthy patients and 30 first degree relatives to determine whether taster status could represent a vulnerability marker. From the study it was found that there was high prevalence of the disease in non-tasters, non tasters also exhibited increased levels of negative and first rank symptoms and poor right nostril odor identification skills relative in PTC tasters. Non-tasters were therefore found to be at a greater risk of getting schizophrenia (Moberg PJ Et al. 2007). Chi Square discussion A Chi-Square analysis was used for the data presented to see if the PTC tasting agreed with the expected frequencies. From the data both Europeans and sub-Saharan Africans had a high percentage of tasters both as homozygous TT and heterozygous Tt. The research showed that the frequencies of PV92 deferred between the Africans and European population. Africans had a probability of tasters at 0.683 and non tasters at 0.317 while Europeans had a probability of tasters at 0.571 and non taster at 0.429. The Pearson Chi-Square showed was 0.001; DF=1, P- value of 0.974, Likelihood ratio Chi Square=0.001, for Europeans. The Pearson Chi-Square showed was 38.738; DF=1, P- value of 0.000, Likelihood ratio Chi Square=38.405, for Sub-Saharan Africa. This showed the students were most likely Europeans with a probability of 0.974. Conclusions It was found that the coding SNPs within the TAS2R38 gene were responsible for the rise in haplotypes. (TT, Tt, tt) The majority of the class population were tasters. This is similar to the results from other researchers that suggest most people in the world are tasters. Both tasters and non tasters are susceptible to cancer and lifestyle diseases. Tasters through avoiding bitter foods especially vegetables and over consuming sweet and sugary foods. 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Rober Fredriksson (2003).The G-Protein-Coupled Receptors in the Human Genome Form Five Main Families. Phylogenetic Analysis, Paralogon Groups, and Fingerprints Read More