Bp Deletion Allele Research Articles

Legacy of a magic gene—CCR5-∆32: From discovery to clinical benefit in a generation

The discovery of the 32-bp deletion allele of the chemokine receptor gene CCR5 showed that homozygous carriers display near-complete resistance to HIV infection, irrespective of exposure. Algorithms of molecular evolutionary theory suggested that the CCR5-∆32 mutation occurred but once in the last millennium and rose by strong selective pressure relatively recently to a ~10% allele frequency in Europeans. Several lines of evidence support the hypothesis that CCR5-∆32 was selected due to its protective influence to resist Yersinia pestis, the agent of the Black Death/bubonic plague of the 14th century. Powerful anti-AIDS entry inhibitors targeting CCR5 were developed as a treatment for HIV patients, particularly those whose systems had developed resistance to powerful anti-retroviral therapies. Homozygous CCR5-∆32/∆32 stem cell transplant donors were used to produce HIV-cleared AIDS patients in at least five "cures" of HIV infection. CCR5 has also been implicated in regulating infection with Staphylococcus aureus, in recovery from stroke, and in ablation of the fatal graft versus host disease (GVHD) in cancer transplant patients. While homozygous CCR5-∆32/32 carriers block HIV infection, alternatively they display an increased risk for encephalomyelitis and death when infected with the West Nile virus.

Human leukocyte antigen-G polymorphisms in periodontitis

Objective: This study evaluated human leucocyte antigen-G gene polymorphisms in patients with periodontitis and healthy controls.Material and methods: The insertion/deletion polymorphism of 14 bp and a single nucleotide polymorphism (SNP) C > G on the position +3142 of the 3′ untranslated region of the gene were analyzed in chronic periodontitis (n = 62), aggressive periodontitis (n = 24) patients and healthy individuals (n = 47).Results: Considering the 14 bp insertion/deletion, a significant deviation from Hardy-Weinberg expectations in the chronic periodontitis group was observed, but not in the other groups. No significant deviations were observed in patients and control groups considering the +3142 C > G SNP. A significant increased frequency of homozygotes for the 14 bp deletion allele was observed in the chronic periodontitis group as compared to controls. This group also presented a higher frequency of the deletion allele, which was marginally not significant. Concerning this polymorphism, no significant differences were observed between the aggressive periodontitis and healthy control groups. In addition, no significant differences were seen amongst patients and controls when considering the +3142 C > G frequencies.Conclusion: No differences were found amongst patients and controls when considering the +3142 C > G SNP haplotypes frequencies, but a significant increased frequency of homozygotes for the 14 bp deletion allele was observed in chronic periodontitis patients compared to healthy controls, suggesting a susceptibility role of this polymorphism in the pathogenesis of this condition.

Gene polymorphism and HLA-G expression in patients with childhood-onset systemic lupus erythematosus: A pilot study.

Human leukocyte antigen-G (HLA-G) presents inhibitory functions in immune cells and is located in a chromosomal region associated with systemic lupus erythematosus (SLE) susceptibility. Polymorphisms in 3' untranslated region (3'UTR) of HLA-G gene may influence protein expression. To date, no study analyzing HLA-G polymorphism and expression in childhood-onset systemic lupus erythematosus (cSLE) has been conducted. Therefore, we investigated the influence of HLA-G 3'UTR polymorphisms in 50 cSLE patients and 144 healthy controls. For the expression analysis, the control group included 26 healthy individuals. No significant difference in allele, genotype, and haplotype frequencies was observed between patients and control group. However, both the 14 bp deletion allele (odds ratio [OR] = 2.76, 95% confidence interval [CI] = 1.17-6.52, P = .028) and the 14 bp deletion-deletion genotype (OR = 8.00, 95% CI = 1.57-40.65, P = .006) showed an association with lupus nephritis. After Bonferroni correction, none P-value remained statistically significant. Regarding HLA-G expression, no significant difference was observed between plasma levels of cSLE patients (56.02 U/mL, interquartile range [IQR] = 37.54-75.41) and control group (49.2 U/mL, IQR = 27.84-154.4, P = .952). However, when the patients were stratified according to clinical manifestations, patients with hematological manifestations showed a lower plasma concentration of soluble HLA-G (sHLA-G) (47.08 U/mL, IQR = 34.15-61.56) than patients with no hematological manifestations (65.26 U/mL, IQR = 47.69-102.60, P = .013). These results suggest that HLA-G polymorphism has small effect on cSLE susceptibility and that sHLA-G may be involved in the pathogenesis of the disease.

A 50 bp deletion in the SOD1 promoter lowers enzyme expression but is not associated with ALS in Sweden

Mutations in the superoxide dismutase (SOD1) gene have been linked to amyotrophic lateral sclerosis (ALS). A 50 base pair (bp) deletion of SOD1 has been suggested to reduce transcription and to be associated with later disease onset in ALS. This study was aimed to reveal if the 50 bp deletion influenced SOD1 enzymatic activity, occurrence and phenotype of the disease in a Swedish ALS/control cohort. Blood samples from 512 Swedish ALS patients and 354 Swedish controls without coding SOD1 mutations were analysed for the 50 bp deletion allele. The enzymatic activity of SOD1 in erythrocytes was analysed and genotype-phenotype correlations were assessed. Results demonstrated that the genotype frequencies of the 50 bp deletion were all found to be in Hardy-Weinberg equilibrium. No significant differences were found for age of onset, disease duration or site of onset. SOD1 enzymatic activity showed a statistically significant decreasing trend in the control group, in which the allele was associated with a 5% reduction in SOD1 activity. The results suggest that the 50 bp deletion has a moderate reducing effect on SOD1 synthesis. No modulating effects, however, were found on ALS onset, phenotype and survival in the Swedish population.

The Dihydrofolate Reductase 19 bp Polymorphism Is Not Associated with Biomarkers of Folate Status in Healthy Young Adults, Irrespective of Folic Acid Intake1–3

Background: Dihydrofolate reductase (DHFR) is essential for the conversion of folic acid to active folate needed for one-carbon metabolism. Common genetic variation within DHFR is restricted to the noncoding regions, and previous studies have focused on a 19 bp deletion/insertion polymorphism (rs70991108) within intron 1. Reports of an association between this polymorphism and blood folate biomarker concentrations are conflicting.Objective: In this study, we evaluated whether the DHFR 19 bp deletion/insertion polymorphism affects circulating folate biomarkers in, to our knowledge, the largest cohort to address this question to date.Methods: Healthy young Irish individuals (n = 2507) between 19 and 36 y of age were recruited between February 2003 and February 2004. Folic acid intake from supplements and fortified foods was assessed with the use of a customized food intake questionnaire. Concentrations of serum folate and vitamin B-12, red blood cell (RBC) folate, and plasma total homocysteine (tHcy) were measured. Data were analyzed with the use of linear regression models.Results: Folic acid intake was positively associated with serum (P < 0.0001) and RBC (P = 0.0005) folate concentration and was inversely associated with plasma tHcy (P = 0.001) as expected. The DHFR 19 bp polymorphism was not significantly associated with either serum (P = 0.82) or RBC (P = 0.21) folate, or plasma tHcy (P = 0.20), even in those within the highest quintile of folic acid intake (>326 μg folic acid/d; P = 0.96). A nonsignificant trend toward lower RBC folate by genotype (P = 0.09) was observed in the lowest folic acid intake quintile (0–51 μg/d).Conclusion: In this cohort of healthy young individuals, the DHFR 19 bp deletion allele did not significantly affect circulating folate status, irrespective of folic acid intake. Our data rule out a strong functional effect from this polymorphism on blood folate concentrations.

Effects of RAGE Gene Polymorphisms on the Risk and Progression of Hepatocellular Carcinoma.

Hepatocellular carcinoma (HCC) is a common malignancy of the liver, whose heterogeneous incidence reflects genetic variations among individuals in the main risk factors. The receptor for advanced glycosylation endproducts (RAGE) is a multiligand receptor and known to be implicated in various pathogenic conditions, such as diabetes, inflammatory disorder, Alzheimer disease, and cancer. In this study, the impact of RAGE gene polymorphisms on the susceptibility to hepatocarcinogenesis was explored. Four single-nucleotide polymorphisms (SNPs), rs184003 (1704G > T), rs1800624 (−374T > A), rs1800625 (−429T > C), and rs2070600 (Gly82Ser), as well as 1 gene polymorphism of RAGE gene, a 63 bp deletion allele (−407 to −345) were analyzed between 300 cancer-free subjects and 265 HCC cases. We detected a significant association of rs1800625 with the increased risk of HCC (odds ratio [OR], 2.565; 95% confidence interval [CI], 1.492–4.409 and adjusted odds ratio [AOR], 2.568; 95% CI, 1.418–4.653). However, patients who possess at least 1 polymorphic allele of rs1800625 are less prone to develop late-stage (stage III/IV, OR, 0.502; 95% CI, 0.243–1.037; P = 0.059 and AOR, 0.461; 95% CI, 0.219–0.970; P = 0.041) and large-size tumors (OR, 0.398; 95% CI, 0.183–0.864; P = 0.017 and AOR, 0.351; 95% CI, 0.157–0.781; P = 0.010). Furthermore, individuals bearing specific haplotypes of 4 RAGE SNPs tested are more inclined to have HCC. In conclusion, our data suggest a correlation of RAGE gene polymorphism rs1800625 with the early stage of liver tumorigenesis and implicate its protective role in the progression of HCC.

HLA-G may predict the disease course in patients with early rheumatoid arthritis

The current management of early rheumatoid arthritis (ERA) is to start an intensive treatment as soon as possible. To avoid under/overtreatment, it is important to identify reliable ERA evolution biomarkers. HLA-G molecules has been associated with rheumatoid arthritis, suggesting a role in disease regulation. HLA-G antigens are expressed as membrane bound and soluble isoforms (mHLA-G, sHLA-G) that act as ligand for immune-inhibitory receptors (ILT2, ILT4, KIR2DL4). Expression of HLA-G is influenced by a 14 bp insertion/deletion polymorphism in exon 8 of the gene, where the deletion is associated with mRNA stability. We analyzed 23 ERA patients during a 12 months follow-up disease treatment for sHLA-G, IL-1beta, IL-6, IL-10 and TNF-alpha levels in plasma samples by ELISA, mHLA-G and ILT2 expression on peripheral blood CD14 positive cells by flow cytometry and typed HLA-G 14 bp deletion/insertion polymorphism by Real-Time PCR. Disease status (DAS28), ultrasonography with power Doppler and laboratory data were checked. Cytokine levels confirmed the anti-inflammatory effect of the treatment. sHLA-G, mHLA-G and ILT2 expression inversely correlated with DAS28 disease scores. The frequency of 14 bp deletion allele increased in patients with disease remission. Based on these results, HLA-G may be a candidate biomarker to evaluate early prognosis and disease activity in ERA patients.

Smoking in adult attention-deficit/hyperactivity disorder: Interaction between 15q13 nicotinic genes and Temperament Character Inventory scores

Adults with ADHD smoke cigarettes at a higher rate than normal subjects. Nicotine has been shown to significantly improve clinical ADHD symptoms as measured by the Clinical Global Impression scale (CGI) as well as by measures of attention, vigour and arousal in ADHD subjects. In this study we hypothesized that the allele 113bp in D15S1360 marker at CHRNA7 and the 2 bp deletion allele at CHRFAM7A are associated with increased smoking in a sample of 90 DSM-IV patients affected by Adult ADHD. Temperament and Character Inventory (TCI) scores were included as covariates in the analysis to distinguish the contribution of personality traits from the contribution of the nicotinic genes under investigation. Smoking status was determined from the medical history questionnaire, and there were 35 current smokers and 55 non-smokers. Single marker associations and the CHRNA7–CHRFAM7A interaction were calculated by logistic regression, considering the 113 bp and the −2 bp deletion in a dominant model. No association of these genes with smoking was observed. Similarly, no significant interaction between the genes was observed in the logistic model. However, Persistence score of the TCI was significantly associated with smoking status. Further investigation on the hypothesis of the molecular interaction between CHRNA7 and CHRFAM7A genes is warranted.

Smoking in adult attention-deficit/hyperactivity disorder: Interaction between 15q13 nicotinic genes and Temperament Character Inventory scores

Adults with ADHD smoke cigarettes at a higher rate than normal subjects. Nicotine has been shown to significantly improve clinical ADHD symptoms as measured by the Clinical Global Impression scale (CGI) as well as by measures of attention, vigour and arousal in ADHD subjects. In this study we hypothesized that the allele 113bp in D15S1360 marker at CHRNA7 and the 2 bp deletion allele at CHRFAM7A are associated with increased smoking in a sample of 90 DSM-IV patients affected by Adult ADHD. Temperament and Character Inventory (TCI) scores were included as covariates in the analysis to distinguish the contribution of personality traits from the contribution of the nicotinic genes under investigation. Smoking status was determined from the medical history questionnaire, and there were 35 current smokers and 55 non-smokers. Single marker associations and the CHRNA7-CHRFAM7A interaction were calculated by logistic regression, considering the 113 bp and the -2 bp deletion in a dominant model. No association of these genes with smoking was observed. Similarly, no significant interaction between the genes was observed in the logistic model. However, Persistence score of the TCI was significantly associated with smoking status. Further investigation on the hypothesis of the molecular interaction between CHRNA7 and CHRFAM7A genes is warranted.

Investigating the association of chemokine receptor 5 (CCR5) polymorphism with cervical cancer in human papillomavirus (HPV) positive patients

HPV is the most responsible of cervical cancer. It is known that chemokines are important determinants of the early inflammatory response. The CC chemokine receptor 5 (CCR5) gene is involved in the chemotaxis of leukocytes toward inflammation sites. In the present study, polymerase chain reactions (PCR) in genomic DNA samples, using specific CCR5 oligonucleotide primers surrounding the breakpoint deletion, detected a 225bp product from the normal CCR5 allele and a 193bp product from the 32bp deletion allele. The wild type genotype was prevalent in both group, but it wasn’t statistically significant with χ² =1,519 (2 degrees of freedom; p>0.05). Once there is a small number of 32 allele carriers, further studies are needed to clarify the role of CCR5 in the cervical cancer.

Impact of Δ32-CCR5 heterozygosity on HIV-1 genetic evolution and variability—A study of 4 individuals infected with closely related HIV-1 strains

A cluster of four patients acutely infected with a genetically almost identical virus, allowed us to investigate genetic variability and disease progression in early HIV-1 infection with minimal interference of virus specific factors. Two of the patients were heterozygous for the 32-bp deletion in the CCR5 coreceptor gene. Both showed a slower disease progression with lower viral load levels and a reduced rate of genetic evolution compared to the patients with normal CCR5 alleles. During 3 years of treatment-free follow-up, the mean pairwise genetic distance increased with 1.45% and 1.58% in the two patients with a 32-bp deletion allele compared to 3.05% and 3.57% in the two patients with normal CCR5 alleles. The observed relation between slower disease progression and a reduced evolutionary rate illustrates the influence of the virus replicative capacity, here most possibly hampered by the CCR5 heterozygosity in two of the four individuals, on the genetic evolution of the virus in the host.

Association study of CCR5 delta 32 polymorphism among the HLA‐DRB1 Caucasian population in Northern Paraná, Brazil

Chemokines are important determinants of early inflammatory response. The CC chemokine receptor 5 (CCR5) delta 32 variant results in a nonfunctional form of the chemokine receptor and has been implicated in a variety of immune-mediated diseases. In the present study, polymerase chain reaction (PCR) for genomic deoxyribonucleic acid (DNA) samples, using specific CCR5 oligonucleotide primers surrounding the breakpoint deletion, detected a 225-basepair (bp) product from the normal CCR5 allele and a 193-bp product from the 32 bp deletion allele. Human leukocyte antigen (HLA) class II (DRB1) typing was performed by PCR-sequence-specific primer (PCR-SSP). The aim of this study was to evaluate the association of HLA-DRB1 and CCR5 genetic polymorphisms. To evaluate the frequency distributions of CCR5 delta 32 polymorphisms in a Brazilian population and their association with allelic distribution of HLA genes, DRB1; a total of 120 Caucasian individuals from northern Paraná, Brazil, were tested. The CCR5/CCR5 genotype was found in 108 individuals (90%) and only one carried the CCR5 delta 32 allele homozygous genotype (0.0238), while 12 (10%) carried the CCR5 delta 32 allele heterozygous genotype. The observed frequency for the CCR5 delta 32 allele was 0.05 in the population studied. The results revealed a CCR5 delta 32 allele occurrence with HLA-DRB1(*)01 and DRB1(*)04 (P<0.05). It is possible that HLA-DRB1(*)01 and DRB1(*)04 alleles could be associated with the delta 32-bp deletion of CCR5.

A closed-tube assay for genotyping of the 32-bp deletion polymorphism in the chemokine receptor 5 (CCR5) gene: Dissociation analysis of amplified fragments of DNA

We have developed a closed-tube assay for determination of the chemokine receptor type 5 (CCR5) 32-bp deletion allele, which protects against infections with HIV and modulates susceptibility to a variety of inflammatory diseases. This assay utilizes dissociation analysis of amplified products in the presence of Sybr Green I for allele discrimination. After having established robust conditions for the assay, we used it to genotype 590 unknown DNA samples. A blinded comparison with a procedure based upon agarose gel electrophoresis of amplified material revealed complete concordance between the two procedures. Our closed-tube assay is inexpensive and easy to carry out. Furthermore, it reduces or eliminates the risk of carry-over contamination with previously amplified products. The insights gained in this study can be applied to develop assays for genotyping of other insertion/deletion polymorphisms based upon differences in T(m) of allele-specific amplicons.

Association Between the CCR5 32-bp Deletion Allele and Late Onset of Schizophrenia

The 32-bp deletion allele in chemokine receptor CCR5 has been associated with several immune-mediated diseases and might be implicated in schizophrenia as well. The authors genotyped DNA samples from 268 schizophrenia patients and 323 healthy subjects. Age at first admission to a psychiatric hospital department served as a measure of disease onset. Patients and comparison subjects differed marginally in their genotype distribution, with a slightly higher frequency of the deletion allele seen in the patients. The authors found the deletion allele to be associated with higher age at first admission. After age at first admission was analyzed as a continuous variable, it was dichotomized using 40 years as the cutoff. With this approach the authors found that genotype distributions of patients with age at first admission above the cutoff (possible cases of late-onset schizophrenia) and healthy subjects differed significantly. This was reflected in an increased frequency of the deletion allele in the patient subgroup. Patients with ages at first admission below and above 40 years significantly differed in distribution of genotypes and alleles, with an overrepresentation of the deletion allele in the latter subgroup of patients. These findings suggest that the CCR5 32-bp deletion allele is a susceptibility factor for schizophrenia with late onset. Alternatively, the CCR5 32-bp deletion allele may act as a modifier by delaying the onset of schizophrenia without affecting the disease susceptibility.

CC-chemokine receptor five gene polymorphism in primary IgA nephropathy: The 32 bp deletion allele is associated with late progression to end-stage renal failure with dialysis

The chemokine (CK) receptor 5 (CCR5) is necessary for two adjacent cysteines (CC)-CKs such as Regulated upon Activation Normal T cell Expressed and Secreted, a/o Macrophage Inflammatory Protein 1alpha/beta to mediate their inflammatory properties. The CCR5 gene polymorphism with 32-basepair deletion (d32) leads to receptor inactivation/dysfunction in homo/heterozygous individuals. We have evaluated its role in both initiation and/or progression of primary immunoglobulin A (IgA) nephropathy (IGAN) in a case-control study involving a prospective cohort of 318 IGAN patients and a matched group of 294 controls. Genotyping was performed by a two-specific primers single polymerase chain reaction technique: normal allele (nl) vs d32 allele. The d32 allele frequency was not different in patients (11.0%) vs controls (8.3%), indicating no significant influence on IGAN initiation. Genotype to clinical phenotype correlation demonstrated that progression to renal/patient death was associated with the d32 allele: 18.2% (12 out of 66 with d32) vs 8.3% (21 out of 252); chi(2)=6.73; P=0.017. The Kaplan-Meier survival without renal/patient death was worse in d32-positive patients (log-rank test; P=0.002). The Cox regression analyses confirmed that the nl/nl genotype was a significant and independent protective factor for progression to end-stage renal failure (ESRF)/dialysis: beta/standard error (s.e.)=-3.1; chi(2)=9.5; relative risk=0.31 (95% confidence interval 0.15-0.65); P=0.002. The d32-CCR5 polymorphism played a significant role in the progression of primary IGAN, with the nl/nl genotype being an independent protective factor for late progression towards ESRF/dialysis. These data raise question about the usefulness of systematic CCR5 genotyping in IGAN patients.

Frequency of the CCR5-Δ32 Mutation in the Atlantic Island Populations of Madeira, the Azores, Cabo Verde, and São Tomé e Príncipe

There is evidence that the CCR5-delta32 mutation confers protection against HIV-1 infection to homozygous individuals. It is believed that this mutation spread through Europe with the Vikings and that it has been subjected to positive selection, leading to a high frequency in Europe (approximately 10%). We carried out the present study to determine the 32-bp deletion allele and genotype frequencies of the CCR5 gene (CCR5-delta32) in the Atlantic island populations of Madeira, the Azores, Cabo Verde, and São Tomé e Principe. These Atlantic archipelagos were all colonized by the Portuguese in the 15th and 16th centuries, but the latter two received most of their settlers from the West African coast. The frequency of the CCR5-delta32 mutation varies between 0% in São Tomé e Príncipe and 16.5% in the Azores. The Azores Islands have one of the highest frequencies of homozygotes found in Europe (4.8%). There are significant differences (P < 0.05) between some of these populations, for example, between São Tomé e Príncipe and Cabo Verde, and even within populations (e.g., Portugal, Madeira, and the Azores).

Polymorphisms in Genes of Folate Metabolism and Response to High-Dose Methotrexate in Patients with Primary Central Nervous System Lymphoma.

The antifolate methotrexate (MTX) was shown to be the single most-effective agent in first-line treatment of patients with primary central nervous system lymphoma (PCNSL) when given intravenously in high doses. MTX inhibits 5,10-methylentetrahydrofolate reductase (MTHFR) as well as thymidylate synthase (TS) in target cells what eventually results in decreased DNA synthesis. Intracellular uptake of both folate and MTX is mediated by the reduced folate carrier (RFC). Genetic polymorphisms for all three proteins were described: a C to T base transition at nucleotide 667 (C677T) and an A to C transition at 1298 (A1298C) of MTHFR; a 28-base pair (bp) tandemly repeated sequence polymorphic in the numbers of the repeat (2R/2R; 3R/3R; and 2R/3R) in the 5′-UTR of TS; a 6bp insertion-(+6bp)/deletion(−6bp)-polymorphism in the 3′-UTR of TS; and a polymorphism at nucleotide 80 (G80A) of RFC. We hypothesized that these polymorphisms may be directly linked to response, survival and toxicity in patients with PCNSL who are treated with single high-dose MTX. We prospectively collected blood from 152 subjects who were enrolled into a German multicenter PCNSL trial. They were scheduled to receive HD-MTX 4 g/m2 every 2 weeks. Genomic DNA was extracted from mononuclear cells using QIAGEN DNA Blood Mini Kit®. Genotyping of the two MTHFR (C677T; A1298C) and the RFC (G80A) single nucleotide polymorphisms (SNPs) was performed by melting point analysis with Master Hybridization Probes® using the Light Cycler® technology. Genotyping of the TS 28bp tandem/triplet repeats in the 5′-UTR was performed by conventional PCR followed by high resolution agarose gel electrophoresis. The TS +6bp/−6bp polymorphism in the 3′-UTR was analyzed with PCR, followed by restriction enzyme digest with draI and agarose gel electrophoresis. The fragment sizes were 70 bp and 88 bp for the 6 bp insertion allele and 152 bp for the 6 bp deletion allele. Allele frequencies for heterozygosity and for homozygous mutations of the two MTHFR and the RFC SNPs as well as of the two TS polymorphisms were as expected for a Caucasian population. For the currently 120 evaluable patients logistic regression analysis, Armitage Trend test and Kaplan-Meier survival curves were performed to analyze the role of the polymorphisms as potential predictors for MTX response. Up to now, we only found a trend for an association between response to treatment and survival for the 2 MTHFR mutations. We will analyze haematological and non-haematological toxicities which will be presented at the meeting with updated results for survival and response in the patients who will have completed treatment until then.

Distribution of the mutated Δ32 allele of the CCR5 gene in a Sicilian population

The CCR5 gene encodes a cell-surface chemokine receptor molecule that serves as a co-receptor for macrophage-tropic strains of human immunodeficiency virus type 1 (HIV-1). A mutation in this gene may alter the expression or the function of the protein product, thereby altering chemokine binding and/or signalling or HIV-1 infection of cells that normally express CCR5 protein. Individuals homozygous for a 32-bp deletion allele of CCR5 (CCR5 delta32), heritable as a Mendelian trait, are relatively resistant to HIV-1 infection. The CCR5 delta32 mutation is present in the Caucasian population at different frequencies. The aim of this study was to investigate the frequency of truncated alleles of the CCR5 delta32 gene in a Sicilian population, as the interpopulation variation in CCR5 delta32 frequency may be a significant factor in the prediction of AIDS endemicity in future studies. We examined 901 healthy individuals from several Sicilian provinces. We found a mean (+/- standard deviation) delta32 allele frequency (fr) of 0.04 +/- 0.012. The highest value was observed in the province of Messina, with a mean delta32 allele frequency of 0.06 +/- 0.024, where we collected samples from a cohort of 114 HIV-1-infected individuals. The observed frequency amongst these patients was quite low (fr = 0.03 +/- 0.031) compared to the healthy population, although the difference was not statistically significant.

Association of CCR5 Δ32 deletion with early death in multiple sclerosis

Purpose: The interaction between chemokines and their receptors is extremely important in controlling T cell migration into sites of CNS inflammation. Because trafficking of inflammatory T cells into the central nervous system (CNS) is a key player in the pathogenesis of multiple sclerosis (MS), we investigated the possible association of CCR5 Δ32 deletion in this disorder.Methods: DNA isolated from postmortem brain tissue samples of 132 patients with MS and from blood tissue samples of 163 gender and ethnicity-matched healthy controls was used to screen for the CCR5 Δ32 deletion allele.Results: An increased frequency of 32-bp deletion allele was found to be associated with early death (P = 0.00005) and with a progressive reduction in the years of survival (onset to death). The death hazard ratio of CCR5 with deletion versus no deletion was 2.12, suggesting that MS patients with the 32-bp deletion have twice the mortality rate of patients with the normal genotype. This effect was more significant in females (hazard ratio 3.58).Conclusion: A strong association of the CCR5 Δ32 deletion with early death could serve as a prognostic marker for MS.

New 19 bp deletion polymorphism in intron-1 of dihydrofolate reductase (DHFR): a risk factor for spina bifida acting in mothers during pregnancy?

Up to 72% of spina bifida cystica (SB) is preventable by maternal periconceptual folic acid supplementation. The C677T allele of the methylenetetrahydrofolate reductase (MTHFR) gene and some other functional polymorphisms are risk factors for SB in some populations. However, despite extensive study, the genetic risk factors for SB are incompletely understood. Polymorphic alleles that diminish bioavailability of reduced folate in the mother during pregnancy could contribute to SB in her fetus, acting in the mother as teratogenic alleles. We recently discovered a polymorphic 19 bp deletion allele (frequency 0.45) within intron-1 of dihydrofolate reductase (DHFR) that is a good candidate for such a genetic factor. Since there is precedence for intron-1 regulatory elements and the deletion allele removes a potential Sp1 transcription factor binding site, we hypothesized that the deletion allele could be functional and act in SB mothers to increase the risk of SB in her fetus. We found that homozygosity for this deletion allele was significantly more frequent in SB mothers, but not in SB fathers or patients, compared with controls and was associated with a significantly increased odds ratio (OR) (2.035) of being an SB mother compared with other genotypes. Genotype distribution obeyed the constraints of Hardy-Weinberg equilibrium in controls, SB patients and fathers, but not in SB mothers. If confirmed, these findings could lead to improved forms of folate supplementation for pregnancy. About half of dietary folates and all of folic acid supplements must be reduced by DHFR to be available for mother and fetus. Reduced folates could be preferable for supplements during pregnancy to prevent SB.