APOL1, CDKN2A/CDKN2B, and HDAC9 polymorphisms and small vessel ischemic stroke

OBJECTIVE

Worldwide, the highest frequencies of APOL1-associated kidney variants are found in indigenous West Africans among whom small vessel disease (SVD) ischemic stroke is the most common stroke phenotype. The objective of this study was to investigate the association and effect sizes of 23 selected SNPs in 14 genes of relevance, including the APOL1 G1 variants, with the occurrence of SVD ischemic stroke among indigenous West African participants in the Stroke Investigative Research and Education Network (SIREN) Study.

MATERIALS AND METHODS

Cases were consecutively recruited consenting adults (aged 18 years or older) with neuroimaging-confirmed first clinical stroke. Stroke-free controls were ascertained using a locally validated version of the Questionnaire for Verifying Stroke-Free Status (QVSFS). Logistic regression models adjusting for known vascular risk factors were fitted to assess the associations of the 23 SNPs in rigorously phenotyped cases (N = 154) of SVD ischemic stroke and stroke-free (N = 483) controls.

RESULTS

Apolipoprotein L1 (APOL1) rs73885319 (OR = 1.52; CI: 1.09-2.13, P-value = .013), rs2383207 in CDKN2A/CDKN2B (OR = 3.08; CI: 1.15-8.26, P -value = .026) and rs2107595 (OR = 1.70; CI: 1.12-2.60, P-value = .014) and rs28688791 (OR = 1.52; CI: 1.03-2.26, P-value = .036) in HDAC9 gene were associated with SVD stroke at 0.05 significance level. Polymorphisms in other genes did not show significant associations.

CONCLUSION

This is the first report of a specific association of APOL1 with a stroke subtype. Further research is needed to confirm these initial findings and deepen understanding of the genetics of stroke in people of African ancestry with possible implications for other ancestries as all humans originated from Africa.

Persistent infection with neurotropic herpes viruses and cognitive impairment

BACKGROUND

Herpes virus infections can cause cognitive impairment during and after acute encephalitis. Although chronic, latent/persistent infection is considered to be relatively benign, some studies have documented cognitive impairment in exposed persons that is untraceable to encephalitis. These studies were conducted among schizophrenia (SZ) patients or older community dwellers, among whom it is difficult to control for the effects of co-morbid illness and medications. To determine whether the associations can be generalized to other groups, we examined a large sample of younger control individuals, SZ patients and their non-psychotic relatives (n=1852). Method Using multivariate models, cognitive performance was evaluated in relation to exposures to herpes simplex virus type 1 (HSV-1), herpes simplex virus type 2 (HSV-2) and cytomegalovirus (CMV), controlling for familial and diagnostic status and sociodemographic variables, including occupation and educational status. Composite cognitive measures were derived from nine cognitive domains using principal components of heritability (PCH). Exposure was indexed by antibodies to viral antigens.

RESULTS

PCH1, the most heritable component of cognitive performance, declines with exposure to CMV or HSV-1 regardless of case/relative/control group status (p = 1.09 × 10-5 and 0.01 respectively), with stronger association with exposure to multiple herpes viruses (β = -0.25, p = 7.28 × 10-10). There were no significant interactions between exposure and group status.

CONCLUSIONS

Latent/persistent herpes virus infections can be associated with cognitive impairments regardless of other health status.

A polymorphism in SOD2 is associated with development of Alzheimer's disease

Genes involved in cellular mechanisms to repair oxidative damage are strong candidates as etiologic factors for Alzheimer's disease (AD). One important enzyme involved in this mechanism is superoxide dismutase 2 (SOD2). The gene for this enzyme lies within a single haplotype block at 6q25.3, a region showing evidence for linkage to AD in a genome scan. We genotyped four single nucleotide polymorphisms (SNPs) in SOD2 in families of the National Institute of Mental Health-AD Genetics Initiative (ADGI): rs2758346 in the 5' untranslated region (UTR), rs4880 in exon 2, rs2855116 in intron 3 and rs5746136 in the 3'UTR. Under a dominant model, family-based association tests showed significant evidence for association of AD with the first three loci in a candidate gene set of families with individuals having age of onset of at least 50 years and two affected and one unaffected sibling, and in a late-onset subset of families (families with all affected individuals having age of onset of at least 65 years) from the full ADGI sample. The alleles transmitted more frequently to cases than expected under the null hypothesis were T, C, G, and G. Global tests of the transmission of haplotypes indicate that the first two loci have the most consistent association with risk of AD. Because of the high linkage disequilibrium in this small (14 kb) gene, and the presence of 100 SNPs in this gene, 26 of which may have functional significance, additional genotyping and sequencing are needed to identify the functionally relevant SNP. We discuss the importance of our findings and the relevance of SOD2 to AD risk.

Association studies of transforming growth factor-beta 1 and Alzheimer's disease

Substantial laboratory evidence suggests Transforming Growth Factor-beta1 (TGFB1) is linked to Alzheimer's Disease (AD) pathology. The purpose of the study was to estimate the genetic association of TGFB1 with AD while controlling for apolipoprotein E4 allele (APOE4) status, the only well-established genetic risk factor for AD. Two study populations were genotyped for the TGFB1-509 and +869 single nucleotide polymorphisms (SNPs) that have been associated with TGFB1 levels. Constituting these populations were 203 families from the NIMH AD Genetic Initiative with at least two affected siblings and a normal sibling, and a population of 126 African-American (AA) AD cases versus 93 age matched controls. Results from family-based analyses showed a significant association between the TGFB1 -509 SNP and AD for the entire set of 203 families (P = 0.007), and a subset of these families without a homozygous APOE4 family member (P = 0.026). Results from family-based analyses on the TGFB1 +869 SNP were not significant in the 203 families. While associations for the main effects of the TGFB1 +869 and -509 SNP with AD in the AA case-control study were also not significant, results did indicate that TGFB1 may function as an effect modifier of APOE4 risk. Specifically, the odds of AD associated with having at least one APOE4 allele increased in an additive fashion with one or two copies of the higher producer allele when stratified by TGFB1 -509 genotype and by TGFB1 +869 genotype. Results support a role for TGFB1 in AD pathogenesis.

SOURCES: a code for calculating (alpha,n), spontaneous fission, and delayed neutron sources and spectra

SOURCES is a computer code that determines neutron production rates and spectra from (alpha,n) reactions, spontaneous fission and delayed neutron emission owing to the decay of radionuclides in homogeneous media, interface problems and three-region interface problems. The code is also capable of calculating the neutron production rates due to (alpha,n) reactions induced by a monoenergetic beam of alpha particles incident on a slab of target material. The (alpha,n) spectra are calculated using an assumed isotropic angular distribution in the centre-of-mass system with a library of 107 nuclide decay alpha-particle spectra, 24 sets of measured and/or evaluated (alpha,n) cross sections and product nuclide level branching fractions, and functional alpha particle stopping cross sections for Z < 106. Spontaneous fission sources and spectra are calculated with evaluated half-life, spontaneous fission branching and Watt spectrum parameters for 44 actinides. The delayed neutron spectra are taken from an evaluated library of 105 precursors. The code outputs the magnitude and spectra of the resultant neutron sources. It also provides an analysis of the contributions to that source by each nuclide in the problem.

Risk factors and cumulative incidence of anaemia among human immunodeficiency virus-infected children in Uganda

Anaemia has not been well characterised among HIV-infected children in sub-Saharan Africa. Baseline prevalence and cumulative incidence of anaemia (haemoglobin < 110 g/L) were 91.7% and 100% and, for moderate anaemia (haemoglobin < 90 g/L), were 35.1% and 58.4%, respectively, among 225 HIV-infected children followed from 9 to 36 months of age. Hospitalisation, suspected tuberculosis, malaria and height-for-age Z-score <-2 were significantly associated with moderate anaemia. Moderate anaemia and weight-for-height Z-score <-2 were associated with mortality. Anaemia is common and associated with increased mortality in HIV-infected children.

The role of TNF and its receptors in Alzheimer's disease

Tumor necrosis factor (TNF) is an important proinflammatory cytokine that is upregulated in Alzheimer disease (AD) patients and involved with AD genes. Several TNF promoter polymorphisms that increase expression are associated with inflammatory and infectious diseases. We previously reported results that detected a AD associated region near the TNF gene. Using family-based association tests we also reported an association between AD and a TNF haplotype in sibling-pair families, and a significant increase in the mean age of onset for a group of African-American AD patients carrying this same haplotype. Previous reports have shown that that the chromosome 1p and chromosome 12p regions are linked to late-onset AD. These two regions harbor TNF receptors (TNFR) 2 and 1, respectively, and binding to them mediates biological effects of TNF. We found a significant asssociation of a TNFR2 exon 6 polymorphism with late-onset AD in families with no individuals possessing the APOE E4E4 genotype under a dominant model. We found no significant association of three polymorphisms in the TNFR1 gene to AD. These results provide further evidence for the involvement of TNF in the pathogenesis of AD.

Investigation of association of 13 polymorphisms in eight genes in southeastern African American Alzheimer disease patients as compared to age-matched controls

Alzheimer disease (AD) is an emotionally devastating and exceptionally costly disease. Apolipoprotein E (APOE) is a major risk factor gene for AD regardless of age of onset or family history. However, this association may not be as strong or consistent in ethnic groups such as African Americans, raising the possibility of other modifier gene(s). In a group of African American AD patients, a significantly increased risk of AD was associated with two E4 alleles (OR = 5.6; 95% CI = 1.5-21.0) or one E4 allele (OR = 2.5; 95% CI = 1.3-5.0) when compared to E3/E3 genotype, and there was a significant lowering of age of onset for affecteds with E4/E4 genotype as compared to one E2 allele (P = 0.02) or all others (P = 0.03). We also found a significant increase in age of onset with the -308 #2 (A) allele of TNF when compared to AD cases with no #2 allele. A significant increase in age was also demonstrated with the #2 allele (99 base pairs) of the microsatellite TNFa, located approximately 10.5 kb upstream of TNF. When these two alleles were combined with the TNF -238G (#1) allele to give a haplotype, the significant increase in age was still demonstrated. Polymorphisms in the APOE promoter and six other candidate genes did not appear to demonstrate any significant association with our African American AD patients. Our results confirm the established association of APOE4 to AD observed in several ethnic groups, including African Americans. In addition, TNF appears to have some modifying effect in AD, primarily on age of onset, or it could be in linkage disequilibrium with a modifier locus nearby.

Association of a haplotype for tumor necrosis factor in siblings with late-onset Alzheimer disease: the NIMH Alzheimer Disease Genetics Initiative

Tumor necrosis factor (TNF), a proinflammatory cytokine, may be involved in the pathogenesis of Alzheimer disease (AD) based on observations that senile plaques have been found to upregulate proinflammatory cytokines. Additionally, nonsteroidal anti-inflammatory drugs have been found to delay and prevent the onset of AD. A collaborative genome-wide scan for AD genes in 266 late-onset families implicated a 20 centimorgan region at chromosome 6p21.3 that includes the TNF gene. Three TNF polymorphisms, a -308 TNF promoter polymorphism, whose TNF2 allele is associated with autoimmune inflammatory diseases and strong transcriptional activity, the -238 TNF promoter polymorphism, and the microsatellite TNFa, whose 2 allele is associated with a high TNF secretion, were typed in 145 families consisting of 562 affected and unaffected siblings. These polymorphisms formed a haplotype, 2-1-2, respectively, that was significantly associated with AD (P = 0.005) using the sibling disequilibrium test. Singly, the TNFa2 allele was also significantly associated (P = 0.04) with AD in these 145 families. This TNF association with AD lends further support for an inflammatory process in the pathogenesis of AD. Am. J. Med. Genet. (Neuropsychiatr. Genet.) 96:823-830, 2000.

Measles infection in HIV-infected African infants

Measles infection remains a serious threat to child survival in the developing world despite vaccination and treatment with vitamin A. This report reviews the epidemiology of measles in HIV-infected children in Africa. In hospitalized infants, the rate of malnutrition before measles and the rate of death after measles are both higher in HIV-positive than in HIV-negative infants. However, the rates of pneumonia and diarrhea in infants hospitalized with measles are the same in HIV-positive as in HIV-negative infants. In an autopsy study, measles was associated with death in HIV-positive children, only for those over 15 months of age. A cohort study found that infants of HIV-positive women were more likely than infants of HIV-negative women to have measles before 9 months of age, although the rates of complications did not differ between the two groups. The HIV status of the infants and the measles serology were too incomplete to draw firm conclusions, though only 1 of 54 infants tested was seropositive for measles at 6 months of age. In the context of the HIV epidemic, further work is needed to determine the risk of measles and its complications in HIV-positive infants and the optimal age of measles immunization.

Acute disease episodes in a Wuchereria bancrofti-endemic area of Papua New Guinea

Acute disease episodes of Bancroftian filariasis were monitored prospectively in a rural area of Papua New Guinea. The frequency and duration of episodes were recorded for the leg, arm, scrotum, and breast. A very high incidence of acute disease was observed; 0.31 episodes per person-year in the leg alone. Incidence generally increased with age, except in the breast, where episodes were concentrated in the reproductive age range. Males had slightly higher incidence than females in the leg and arm. Chronic disease was strongly associated with acute disease incidence in all locations. Microfilaremia had a statistically significant association with acute disease in the leg, arm, and breast, but not the scrotum. This study again demonstrates the high burden of acute manifestations of lymphatic filariasis, and provides new information on risk factors, which may lead to better understanding of etiology and control prospects.

Reconstruction of advanced mandibular resorption with both subperiosteal and root-form implants

A combination implant reconstruction using both subperiosteal and endosseous root-form implants for advanced mandibular resorption is presented. In theory and practice, physiologic endosseous implant support should prevent further resorption in the mandibular symphysis region. Three patients' post-treatment outcomes demonstrate a complete return of mandibular oral function. The greater risk of mandibular fracture, which is associated with other treatment options (multiple root-form implants or transmandibular implants), is avoided with this treatment approach. With follow-up periods ranging from 6 months to 28 months the three patients are satisfied with comfort, function, and appearance. A long-term follow-up study is planned for future publication.

A single dose of live oral cholera vaccine CVD 103-HgR is safe and immunogenic in HIV-infected and HIV-noninfected adults in Mali

Despite considerable experience with single-dose, live, oral cholera vaccine CVD 103-HgR in Asia, Europe, and the Americas, the vaccine had not been evaluated in sub-Saharan Africa or on individuals infected with human immunodeficiency virus (HIV). We therefore conducted a randomized, placebo-controlled, double-blind, cross-over clinical trial in 38 HIV-seropositive (without clinical acquired immunodeficiency syndrome (AIDS)) and 387 HIV-seronegative adults in Mali to assess its safety and immunogenicity. Adverse reactions (fever, diarrhoea and vomiting) were observed with similar frequency among vaccine and placebo recipients. The vaccine strain was not isolated from the coprocultures of any subject. The baseline geometric mean titre (GMT) of serum vibriocidal antibody was significantly lower in HIV-seropositives (1:23) than in HIV-seronegatives (1:65) (P = 0.002). Significant rises in vibriocidal antibody were observed in 71% of HIV-seronegatives and 58% of HIV-seropositives, and in 40% of HIV-seropositives with CD4+ counts below 500 per microliter. Following immunization, the peak vibriocidal GMT in HIV-seronegatives was 1:584 versus 1:124 in HIV-seropositives (P = 0.0006); in HIV-seropositives with CD4+ counts < 500 per microliter, the peak vibriocidal GMT was 1:40 (P = 0.03 versus other HIV-seropositives). CVD 103-HgR was safe in HIV-infected Malian adults, although serological responses were significantly attenuated among HIV-seropositives (particularly in those with CD4+ counts < 500 per microliter) relative to HIV-seronegatives. These results encourage further evaluations of this single-dose, oral cholera vaccine in high-risk populations such as refugees in sub-Saharan Africa.

ApoE-4 and age at onset of Alzheimer's disease: the NIMH genetics initiative

OBJECTIVE

To explore the impact of apoE-4 on Alzheimer's disease (AD) and its age at onset.

DESIGN

A genetic linkage study using affected relative pairs, predominantly siblings.

SETTING

Three academic medical centers ascertained subjects from memory disorder clinics, nursing homes, and the local community.

SUBJECTS

310 families including 679 subjects with AD by NINCDS/ADRDA and/or Khachaturian criteria and 231 unaffected subjects.

OUTCOME MEASURE

ApoE genotype. ANALYTIC METHODS: Association, affected pedigree member, sibling pair, and lod score analyses.

RESULTS

ApoE-4 was strongly associated with AD in this sample (allele frequency = 0.46 vs. 0.14 in controls, p < 0.000001). Results of lod score, affected pedigree member analysis, and sib-pair analysis also supported apoE-4 as a risk factor for AD. When the sample was stratified on family mean age at onset, the risk conferred by apoE-4 was most marked in the 61 to 65 age group. Individuals with two copies of apoE-4 had a significantly lower age at onset than those with one or no copies (66.4 vs. 72.0, p < 0.001), but individuals with one copy did not differ from those with none. Within families, the individual with the earliest age at onset had, on average, significantly more apoE-4 alleles (p < 0.0001) than the individual with the latest onset.

DISCUSSION

This work supports previous reports of an association between apoE-4 and the development of AD and demonstrates that apoE-4 exerts its maximal effect before age 70. These findings have important implications for the potential use of apoE genotyping for diagnosis and prediction of disease. They also underscore the need to identify additional genetic factors involved in AD with onset beyond age 70 years.

SSCP analysis and sequencing of the human prion protein gene (PRNP) detects two different 24 bp deletions in an atypical Alzheimer's disease family

Alzheimer's disease (AD) is a progressive, degenerative neurological disorder of the central nervous system. AD is the fourth leading cause of death in elderly persons 65 years or older in Western industrialized societies. The etiology of AD is unknown, but clinical, pathological, epidemiological, and molecular investigations suggest it is etiologically heterogeneous. Mutations in the amyloid protein are rare and segregate with the disease in a few early-onset familial AD (FAD) families. Similarities between AD and the unconventional viral (UCV) diseases, and between the amyloid and prion proteins, implicate the human prion protein gene (PRNP) as another candidate gene. Single strand conformation polymorphism (SSCP) analysis was used to screen for mutations at this locus in 82 AD patients from 54 families (30 FAD), vs. 39 age-matched controls. A 24-bp deletion around codon 68 that codes for one of five Gly-Pro rich octarepeats was identified in two affected sibs and one offspring of one late-onset FAD family. Two other affected sibs, three unaffected sibs, and three offspring from this family, in addition to one sporadic AD patient and three age-matched controls, were heterozygous for another octarepeat deletion located around codon 82. Two of the four affected sibs had features of PD, including one who was autopsy-verified AD and PD. Although these deletions were found infrequently in other AD patients and controls, they appear to be a rare polymorphism that is segregating in this FAD family. It does not appear that mutations at the PRNP locus are frequently associated with AD in this population.