Substitution Of Isoleucine Research Articles

IDENTIFICATION OF MUTATION IN THE BEMISIA TABACI (GENN.) PARA SODIUM CHANNEL GENE ASSOCIATED WITH RESISTANCE TO PYRETHROIDS

Mechanism of resistance to lambda-cyhalothrin in highly resistant Bemisia tabaci strain can be explained by the voltage-gated sodium channel which is the primary target site of pyrethroid insecticides. The super knockdown resistance (super-kdr) to pyrethroids is caused by changes at specific sites on the para-type sodium channel protein domain II (IIS4-6). The B. tabaci para-type sodium channel gene was RT-PCR amplified from lab-strain (reference), Parent (first generation after treatment with the insecticide) and generation thirteen after treatment was considered. The mechanisms of resistance to Lambda-cyhalothrin (Karat 20% EC) in a Q biotype, highly resistant Bemisia tabaci strain. Analysis of the sequence of the IIS4-IIS6 region of the para sodium channel gene of lab-strain, Parent and resistant strain (G13) revealed two amino acid replacements compared to that of the SUD-S susceptible strain. One is the leucine to isoleucine substitution at position 925 (L925I) and allele r1-Q1 (GenBank accession no. DQ205206) has identical intron sequences with samples of parent and lab-strain, other is a novel kdr resistant mutation for B. tabaci, a threonine to valine substitution at position (T929V) and alleles r2-Q1 (GenBank accession no DQ205207) has identical intron sequence with G13..

The recognition of γδ TCR to protein antigen does not depend on the hydrophobic I97 residue of CDR3δ

The crystal structure analysis demonstrated that the hydrophobic amino acid residue (isolecuine/leucine/valine) at conserved position 97 of Vdelta2 TCR plays an important role in recognizing the non-peptide antigen. But its importance to protein antigen remains unclear until now. In the present study, we focus on the role of hydrophobic amino acid residue at conserved position 97 of Vdelta2 TCR in complementarity determining region (CDR)3delta-mediated binding to protein antigen. We employed CDR3delta peptide and membrane-engineered gammadelta TCR as detecting molecules with mutated 97 hydrophobic amino acid residue in CDR3delta (nominated as OT10), a Vdelta2 CDR3 sequence derived from tumor infiltrating lymphocytes in ovarian epithelial carcinoma (OEC). Binding assays revealed that OT10 peptide and membrane-engineered gammadelta TCR (gammadelta TCR transfected cells with OT10 sequence) could bind specifically ovarian tumor cell line (SKOV3). The mutant analysis indicated that any amino acid substitution at position deltaI97 could abolish the response of the transfected cells to iso-butylamine, a known non-peptide antigen of gammadelta T cells. But amino acid substitution of isoleucine at position delta97 did not change the responsiveness of gammadelta TCR transfected cell to protein antigen. Our data suggested that a mechanism other than non-peptide antigen might mediate the recognition of Vdelta2gammadelta T cells for protein antigen. This finding may provide a possibility that gammadelta TCR recognize different ligands in diversity manners.

Potassium Channel Silencing by Constitutive Endocytosis and Intracellular Sequestration

Tandem of P domains in a weak inwardly rectifying K(+) channel 1 (TWIK1) is a K(+) channel that produces unusually low levels of current. Replacement of lysine 274 by a glutamic acid (K274E) is associated with stronger currents. This mutation would prevent conjugation of a small ubiquitin modifier peptide to Lys-274, a mechanism proposed to be responsible for channel silencing. However, we found no biochemical evidence of TWIK1 sumoylation, and we showed that the conservative change K274R did not increase current, suggesting that K274E modifies TWIK1 gating through a charge effect. Now we rule out an eventual effect of K274E on TWIK1 trafficking, and we provide convincing evidence that TWIK1 silencing results from its rapid retrieval from the cell surface. TWIK1 is internalized via a dynamin-dependent mechanism and addressed to the recycling endosomal compartment. Mutation of a diisoleucine repeat located in its cytoplasmic C terminus (I293A,I294A) stabilizes TWIK1 at the plasma membrane, resulting in robust currents. The effects of I293A,I294A on channel trafficking and of K274E on channel activity are cumulative, promoting even more currents. Activation of serotoninergic receptor 5-HT(1)R or adrenoreceptor alpha2A-AR stimulates TWIK1 but has no effect on TWIK1I293A,I294A, suggesting that G(i) protein activation is a physiological signal for increasing the number of active channels at the plasma membrane.

A Sequence Variation (I148M) in PNPLA3 Associated with Nonalcoholic Fatty Liver Disease Disrupts Triglyceride Hydrolysis

Obesity and insulin resistance are associated with deposition of triglycerides in tissues other than adipose tissue. Previously, we showed that a missense mutation (I148M) in PNPLA3 (patatin-like phospholipase domain-containing 3 protein) is associated with increased hepatic triglyceride content in humans. Here we examined the effect of the I148M substitution on the enzymatic activity and cellular location of PNPLA3. Structural modeling predicted that the substitution of methionine for isoleucine at residue 148 would restrict access of substrate to the catalytic serine at residue 47. In vitro assays using recombinant PNPLA3 partially purified from Sf9 cells confirmed that the wild type enzyme hydrolyzes emulsified triglyceride and that the I148M substitution abolishes this activity. Expression of PNPLA3-I148M, but not wild type PNPLA3, in cultured hepatocytes or in the livers of mice increased cellular triglyceride content. Cell fractionation studies revealed that ∼90% of wild type PNPLA3 partitioned between membranes and lipid droplets; substitution of isoleucine for methionine at position 148 did not alter the subcellular distribution of the protein. These data are consistent with PNPLA3-I148M promoting triglyceride accumulation by limiting triglyceride hydrolysis.

Calmodulin Release from the IQ Domain of Cav1.3 Channels During Calcium Dependent Inactivation?

Calmodulin (CaM) regulation of CaV channels has long fascinated biophysicists, with structure-function analysis mostly focused on an IQ domain in the carboxy-terminus of channels. It is clear that Ca2+-free CaM (apoCaM) preassociates with the IQ domain before Ca2+ entry through channels (see Liu X et al this meeting), and that Ca2+/CaM has the potential to bind the IQ. Hence, Ca2+-dependent inactivation (CDI) of channels has been thought to result by transducing Ca2+-dependent conformational changes of CaM, all while bound to the IQ. By contrast, functional analysis of our structure of Ca2+/CaM complexed with the IQ domain of CaV2.1 (Structure 16:607) hints that Ca2+/CaM may depart from the IQ domain during channel regulation. To generalize this hypothesis, we here alanine scanned the entire IQ domain of CaV1.3, an exemplary prototype of CaV1 channels with high homology to long-studied CaV1.2. Importantly, alanine substitution likely preserves backbone fold, whereas prior studies often used more disruptive mutations targeting specific loci. As before, alanine substitution of the signature isoleucine strongly suppressed CDI. Suprisingly, however, CDI was strongly diminished only at one other residue, upstream of the central isoleucine. Altering many other sites, presumed important for Ca2+/CaM-IQ binding in crystal structures, left CDI unscathed. Moreover, we homology modeled Ca2+/CaM bound to the CaV1.3 IQ domain, based on x-ray structures of CaV1.2. We then computed (Robetta) the energetic cost of alanine mutations (ΔΔG for binding). If Ca2+/CaM-IQ binding begets CDI, plots of CDI versus ΔΔG should define a Boltzmann function. Instead, a highly scattered relationship was produced. Thus, CDI may involve (partial) departure of Ca2+/CaM from the IQ domain of CaV1.3, to interact with alternative sites (Yang, Ben Johny, & Yue, this meeting). This departure would fundamentally transform our understanding of CaM/channel regulation.

Parvovirus B19 Genotype Specific Amino Acid Substitution in NS1 Reduces the Protein's Cytotoxicity in Culture

A clinical association between idiopathic liver disease and parvovirus B19 infection has been observed. Fulminant liver failure, not associated with other liver-tropic viruses, has been attributed to B19 in numerous reports, suggesting a possible role for B19 components in the extensive hepatocyte cytotoxicity observed in this condition. A recent report by Abe and colleagues (Int J Med Sci. 2007;4:105-9) demonstrated a link between persistent parvovirus B19 genotype I and III infection and fulminant liver failure. The genetic analysis of isolates obtained from these patients demonstrated a conservation of key amino acids in the nonstructural protein 1 (NS1) of the disease-associated genotypes. In this report we examine a conserved residue identified by Abe and colleagues and show that substitution of isoleucine 181 for methionine, as occurs in B19 genotype II, results in the reduction of B19 NS1-induced cytotoxicity of liver cells. Our results support the hypothesis that in the setting of persistent B19 infection, direct B19 NS1-induced cytotoxicity may play a role in idiopathic fulminant liver failure.

Histamine N-methyltransferase Thr105Ile is not associated with Parkinson's disease or essential tremor

A functional variant in the Histamine N-Methyltransferase gene ( HNMT – rs11558538) resulting in a threonine to isoleucine substitution (Thr105Ile) has been shown to impair histamine degradation. Two recent studies reported that the threonine allele of this polymorphism might be a risk factor for Parkinson disease (PD) and essential tremor (ET) development. Although PD and ET are considered different entities, they share some clinical and pathological features, suggesting a possible joint etiology. In this study we assess the role of the Thr105Ile variant in PD and ET development, genotyping the variant in a North American Caucasian PD and ET case-control series. Statistical analysis did not identify any significant association between this variant and PD or ET; therefore, our findings do not support the HNMT Thr105Ile variant as a factor in disease development or a genetic link between the disorders.

A novel mutation spatially remote from the G-domain in IF2 affects the cold stress adaptation of Escherichia coli

In this paper, we describe a new mutation, gicD1, that gives a cold-sensitive phenotype in bacterial cell growth. Complementation analysis showed gicD1 to be allelic to infB. We identify gicD1 to be a valine to isoleucine substitution in initiation factor-2 (IF2) of a residue that seems to be well conserved in eubacterial IF2 proteins. This mutation lies in a region distant from the G-domain to which all earlier reported cold-sensitive mutations cluster. We describe a novel phenotype of the mutant that is suppression of rpsL31-mediated streptomycin resistance in cold. We provide evidence that mutant IF2 specifically interacts with rpsL31 in cold, leading to a bacteriostatic effect on host cells.

Genetic association study of CYP1A1 polymorphisms identifies risk haplotypes in nonsmall cell lung cancer

Lung cancer remains a leading cause of disease globally, with smoking being the largest single cause. Phase I enzymes, including cytochrome P(450), family 1, subfamily A, polypeptide 1 (CYP1A1), are involved in the activation of carcinogens, such as polycyclic aromatic hydrocarbons, to reactive intermediates that are capable of binding covalently to DNA to form DNA adducts, potentially initiating the carcinogenic process. The aim of the present study was to investigate the association of CYP1A1 gene polymorphisms and haplotypes with lung cancer risk. A case-control study was carried out on 1,040 nonsmall cell lung cancer (NSCLC) cases and 784 controls to investigate three CYP1A1 variants, CYP1A1*2A (rs4646903; thymidine to cytosine substitution at nucleotide 3801 (3801T>C)), CYP1A1*2C (rs1048943; 2455A>G; substitution of isoleucine 462 with valine (exon 7)) and CYP1A1*4 (rs1799814; 2453C>A; substitution of threonine 461 with asparagine (exon 7)) using PCR restriction fragment length polymorphism methods. The CYP1A1*2A and CYP1A1*2C variants were significantly over-represented in NSCLC cases compared with controls, whereas the CYP1A1*4 variant was under-represented. CYP1A1 haplotypes (in allele order CYP1A1*4, CYP1A1*2C, CYP1A1*2A) CGC and CGT were associated with an increased risk of lung cancer, whereas AAT was associated with decreased lung cancer risk in this population. The present study has identified risk haplotypes for CYP1A1 in NSCLC and confirmed that CYP1A1 polymorphisms are a minor risk factor for NSCLC.

I440V mutation in C1 esterase inhibitor gene in a patient with hereditary angioedema and its influence to the structure of C1 esterase inhibitor

Objective To assess the mutation in exon 8 of C1 esterase inhibitor （C1INH） gene in a patient with hereditary angioedema （HAE）. Methods Genomic DNA was extracted from a female patient with HAE as well as her mother and a normal human control. The fragment of exon 8 of C1INH gene was amplified by PCR and inserted into plasmid carrier pUC19 with the help of ligase. Then, the recombinant plasmid was transformed into competent cells of E. coli TG1 strains. After culture of positive transformant, plasmid DNA was extracted and subjected to sequencing. SDS-PAGE and Western blot were performed on the sera of the patient to detect the concentration and function of C1INH protein. Results An A1677G mutation at exon 8 of C1INH gene, which resulted in a substitution of isoleucine to valine at codon 440, was found in the patient who suffered from HAE type I. Additionally, SDS-PAGE and Western blot revealed that the molecular weight of CIINH protein was 96 000, but not 105 000 observed in normal human control. Conclusion The newly identified mutation I440V, which is located at P4 residue of reactive center loop in CIINH, may result in conformational alteration of C1INH. Key words: Angioneurotic edema; C1 esterase inhibitors; Variation （genetics）

Role of Amyloid- Glycine 33 in Oligomerization, Toxicity, and Neuronal Plasticity

The aggregation of the amyloid-beta (Abeta) peptide plays a pivotal role in the pathogenesis of Alzheimer's disease, as soluble oligomers are intimately linked to neuronal toxicity and inhibition of hippocampal long-term potentiation (LTP). In the C-terminal region of Abeta there are three consecutive GxxxG dimerization motifs, which we could previously demonstrate to play a critical role in the generation of Abeta. Here, we show that glycine 33 (G33) of the central GxxxG interaction motif within the hydrophobic Abeta sequence is important for the aggregation dynamics of the peptide. Abeta peptides with alanine or isoleucine substitutions of G33 displayed an increased propensity to form higher oligomers, which we could attribute to conformational changes. Importantly, the oligomers of G33 variants were much less toxic than Abeta(42) wild type (WT), in vitro and in vivo. Also, whereas Abeta(42) WT is known to inhibit LTP, Abeta(42) G33 variants had lost the potential to inhibit LTP. Our findings reveal that conformational changes induced by G33 substitutions unlink toxicity and oligomerization of Abeta on the molecular level and suggest that G33 is the key amino acid in the toxic activity of Abeta. Thus, a specific toxic conformation of Abeta exists, which represents a promising target for therapeutic interventions.

I219V Polymorphism in hMLH1 Gene in Patients Affected with Ulcerative Colitis

hMLH1 gene, lying on chromosome 3p21-23, is a key factor of the mismatch repair (MMR) complex, which amends DNA replication errors. MMR alterations are involved in the development of both hereditary and sporadic forms of colorectal carcinoma related to ulcerative colitis (UC). I219V Polymorphism is located on exon 8 of hMLH1 and provides an aminoacidic substitution of isoleucine to valine, on the protein codon 219. This may affect the speed and fidelity of protein synthesis because of a tRNA paucity or changes in the mRNA secondary structure. Most of the hereditary nonpolyposis colon cancer-associated missense mutations of hMLH1 cause structural changes of the amino- or carboxy-terminal regions, involving the domains that interact with ATP and hPMS2. In this study, we analyzed the hMLH1 I219V polymorphism frequency in colectomized patients with UC. Venous blood from 100 ulcerative patients and 97 apparently healthy subjects has been collected. Out of 100 patients affected with UC, 75 noncolectomized showed an alternating course of disease, while 25 did not respond to the common drugs, and underwent colectomy. Genotyping was performed by polymerase chain reaction and following enzymatic digestion by BccI. No significant differences were found between patients with UC and controls both for genotype and allele frequencies. However, our data show a significant association when colectomized and noncolectomized patients are compared. The frequencies of G homozygosity were 28% in colectomized and 10.7% in noncolectomized patients (p < 0.05, chi(2) = 4.4, Odds ratio = 3.3). The allele frequencies of allele A were 52% in colectomized and 68% in noncolectomized patients; while those of allele G were 48% and 32%, respectively. I219V polymorphism in hMLH1 could influence the clinical course of the disease and lead to resistance to therapy.

Structural Basis of the Radicicol Resistance Displayed by a Fungal Hsp90

Heat shock protein 90 (Hsp90) is a promising cancer drug target, as multiple oncogenic proteins are destabilized simultaneously when it loses its activity in tumor cells. Highly selective Hsp90 inhibitors, including the natural antibiotics geldanamycin (GdA) and radicicol (RAD), inactivate this essential molecular chaperone by occupying its nucleotide binding site. Often cancer drug therapy is compromised by the development of resistance, but a resistance to these Hsp90 inhibitors should not arise readily by mutation of those amino acids within Hsp90 that facilitate inhibitor binding, as these are required for the essential ATP binding/ATPase steps of the chaperone cycle and are tightly conserved. Despite this, the Hsp90 of a RAD-producing fungus is shown to possess an unusually low binding affinity for RAD but not GdA. Within its nucleotide binding site a normally conserved leucine is replaced by isoleucine, though the chaperone ATPase activity is not severely affected. Inserted into the Hsp90 of yeast, this conservative leucine to isoleucine substitution recreated this lowered affinity for RAD in vitro. It also generated a substantially enhanced resistance to RAD in vivo. Co-crystal structures reveal that the change to isoleucine is associated with a localized increase in the hydration of an Hsp90-bound RAD but not GdA. To the best of our knowledge, this is the first demonstration that it is possible for Hsp90 inhibitor resistance to arise by subtle alteration to the structure of Hsp90 itself.

Spontaneous Quinolone Resistance in the Zoonotic Serovar of Vibrio vulnificus

This work demonstrates that Vibrio vulnificus biotype 2, serovar E, an eel pathogen able to infect humans, can become resistant to quinolone by specific mutations in gyrA (substitution of isoleucine for serine at position 83) and to some fluoroquinolones by additional mutations in parC (substitution of lysine for serine at position 85). Thus, to avoid the selection of resistant strains that are potentially pathogenic for humans, antibiotics other than quinolones must be used to treat vibriosis on farms.

T670X KIT Mutations in Gastrointestinal Stromal Tumors: Making Sense of Missense

Chronic myeloid leukemia, gastrointestinal stromal tumors (GISTs), and idiopathic hypereosinophilic syndrome are associated with pathological deregulation of the tyrosine kinases BCR-ABL, KIT, and PDGFRA, respectively. Patients who become resistant to imatinib treatment often develop secondary mutations, the most common of which results in a substitution of isoleucine for threonine at the same location in the ATP-binding domain in all three kinases (in KIT this occurs at amino acid 670). We sought to determine why Thr is always replaced by Ile. All possible point mutations in the DNA triplet codon that could result in amino acid substitutions at Thr670 (Thr670Arg, Thr670Ile, Thr670Lys, Thr670Ala, Thr670Ser, Thr670Pro) were introduced by site-specific mutagenesis of the complementary DNA for a constitutively active, imatinib-sensitive form of the KIT receptor, Delta559/KIT. The resulting mutant KIT proteins were transiently expressed in COS1 African green monkey kidney cells grown with and without imatinib, and cell extracts were analyzed for KIT activation by immunoprecipitation and immunoblotting to determine autophosphorylation levels. We also performed molecular modeling to estimate the relative affinities of wild-type (Thr670) KIT and the KIT mutants for ATP and imatinib. Like the parental strain, Thr670Ala, Thr670Ser, and Thr670Lys mutants were inhibited by 5 microM imatinib, but in comparison, they were only weakly active and Thr670Pro and Thr670Arg were not active at all. Only the Thr670Ile mutant was fully active (autophosphorylated) and resistant to imatinib. These findings were consistent with computer modeling predictions that ranked these mutants Thr - Ile > Ala, Ser > Lys >> Pro according to their affinity for ATP but Thr > Ala, Ser > Lys >Pro - Arg - Ile according to their affinity for imatinib. This combination of in vitro and molecular modeling analyses shows why, among all possible amino acid substitutions at position 670 of KIT, only Ile is naturally selected as a resistance mutant in imatinib-treated GIST patients.

Altered expression of the caffeine synthase gene in a naturally caffeine-free mutant of Coffea arabica

In this work, we studied the biosynthesis of caffeine by examining the expression of genes involved in this biosynthetic pathway in coffee fruits containing normal or low levels of this substance. The amplification of gene-specific transcripts during fruit development revealed that low-caffeine fruits had a lower expression of the theobromine synthase and caffeine synthase genes and also contained an extra transcript of the caffeine synthase gene. This extra transcript contained only part of exon 1 and all of exon 3. The sequence of the mutant caffeine synthase gene revealed the substitution of isoleucine for valine in the enzyme active site that probably interfered with enzymatic activity. These findings indicate that the absence of caffeine in these mutants probably resulted from a combination of transcriptional regulation and the presence of mutations in the caffeine synthase amino acid sequence.

P3-211: Overexpression of the C-terminal fragment of APP altered gene expression profiles in APPV717I-CT100 transgenic mice

Many carboxy-terminal (C-terminal) fragments of the human amyloid precursor protein (APP) are neurotoxic, including β amyloid (Aβ) and APP-CT100. We used a transgenic mouse model expressing the familial Alzheimer's disease (AD) ‘London mutation' with the V717I (valine to isoleucine) substitution within APP-CT100, which includes the Aβ sequence. APPV717I is associated with aggressive early onset dementia and a characteristic increase in the long amyloidogenic form of Aβ (Aβ1–42) in AD brain. β amyloid, in the form of diffuse non-congophilic extracellular plaques, deposits in the brain of transgenic mice expressing APPV717I-CT100 from 6 months of age. To elucidate the neurodegenerative mechanisms of AD, we evaluated several genes that might be involved in APP pathology in 11-month-old APPV717I-CT100 transgenic mice using microarray analysis. We compared the profiles of the altered genes in the hippocampal region of transgenic mice with that of age-matched wild-type transgenic mice. We also clustered the genes associated with apoptosis, cell cycle, cell death, cellular physiology, immune response, signal transduction, and transcription. We selected several genes that might have essential roles in AD pathology and their altered expression in the cortical and hippocampal brain tissues used in the microarray anaysis was confirmed with RT-PCR and Western blot analysis. In addition, the expression pattern of the selected genes was examined in human AD brain by immunohistochemistry and Western blot, and their pathogenic mechanisms were studied in an APP intracellular domain -overexpressing cell culture system. These findings suggest that APPV717I-CT100 overexpression selectively alters the levels of specific transcripts in the brains of transgenic mice. This study provides valuable information about several AD-related genes and their pathogenic roles.

Tetrameric β3‐Peptide Bundles

Tetrameric β³‐Peptide Bundles

The b arg36 contributes to efficient coupling in F1FO ATP synthase in Escherichia coli

In Escherichia coli, the F(1)F(O) ATP synthase b subunits house a conserved arginine in the tether domain at position 36 where the subunit emerges from the membrane. Previous experiments showed that substitution of isoleucine or glutamate result in a loss of enzyme activity. Double mutants have been constructed in an attempt to achieve an intragenic suppressor of the b (arg36-->ile) and the b (arg36-->glu) mutations. The b (arg36-->ile) mutation could not be suppressed. In contrast, the phenotypic defect resulting from the b (arg36-->glu) mutation was largely suppressed in the b (arg36-->glu,glu39-->arg) double mutant. E. coli expressing the b (arg36-->glu,glu39-->arg) subunit grew well on succinate-based medium. F(1)F(O) ATP synthase complexes were more efficiently assembled and ATP driven proton pumping activity was improved. The evidence suggests that efficient coupling in F(1)F(O) ATP synthase is dependent upon a basic amino acid located at the base of the peripheral stalk.

Glutathione S-Transferase P1??Ile105Val Polymorphism is Associated??with Haematological Toxicity in Elderly Rectal Cancer??Patients Receiving Preoperative Chemoradiotherapy

Increasing evidence suggests that common gene polymorphisms may influence the toxicity of various cytotoxic agents used in the treatment of cancer. To evaluate the predictive value of acute toxicity of methylenetetrahydrofolate reductase 677T polymorphism, glutathione S-transferase P1 (GSTP1) substitution of isoleucine with valine at codon 105 (Ile105Val) polymorphism and the tandem repeat polymorphism in the thymidylate synthase gene promoter in elderly patients with rectal cancer receiving preoperative chemoradiotherapy (CRT). From 1994 to 2002, 166 Caucasian patients underwent surgery following CRT for mid-low rectal cancer at a single institution, 42 (male-to-female ratio, 25 : 17) of whom were aged > or =65 years (median age 70 years, range 65-79). The pre-treatment clinical stage was tumour (T) stage 3-4 in 38 patients and node (N)-positive in 29 patients. Patients received external-beam radiotherapy with conventional fractionation and fluorouracil-based chemotherapy. Blood samples were used to extract and amplify DNA. Gene polymorphisms were determined by polymerase chain reaction and restriction enzyme digestion. Acute toxicity to preoperative therapy was reported according to the National Cancer Institute Common Toxicity Criteria, version 2. Univariate and multivariate analyses were performed using one-way analysis of variance and linear regression, respectively. Haematological toxicity (grade 1-2) was observed in 15 of 40 patients for whom toxicity data were available and gastrointestinal toxicity (grade 1-4) in 24 of these same 40 patients. At univariate analysis, female sex (p = 0.036) and GSTP1 Ile105Val (p = 0.0376) were associated with haematological toxicity. At multivariate analysis, GSTP1 Ile105Val polymorphism (p = 0.041) was the only factor found to be associated with haematological toxicity. Patients carrying the Val/Val genotype in the GSTP1 gene had a lower risk of haematological toxicity (odds ratio = 0.322, 95% CI 0.101, 0.957) than patients with the Ile/Ile genotype. GSTP1 Ile105Val polymorphism is a promising marker of potential haematological toxicity in elderly patients with rectal cancer receiving preoperative CRT.