Association of the paternally transmitted copy of common Valine allele of the Val66Met polymorphism of the brain-derived neurotrophic factor (BDNF) gene with susceptibility to ADHD

Attention deficit hyperactivity disorder (ADHD) is a common, highly heritable, neurodevelopmental disorder with onset in early childhood. Genes involved in neuronal development and growth are, thus, important etiological candidates and brain-derived neurotrophic factor (BDNF), has been hypothesized to play a role in the pathogenesis of ADHD. BDNF is a member of the neurotrophin family and is involved in the survival and differentiation of dopaminergic neurons in the developing brain (of relevance because drugs that block the dopamine transporter can be effective therapeutically). The common Val66Met functional polymorphism in the human BDNF gene (rs 6265) was genotyped in a collaborative family-based sample of 341 white UK or Irish ADHD probands and their parents. We found evidence for preferential transmission of the valine (G) allele of BDNF (odds ratio, OR=1.6, P=0.02) with a strong paternal effect (paternal transmissions: OR=3.2, P=0.0005; maternal transmissions: OR=1.00; P=1.00). Our findings support the hypothesis that BDNF is involved in the pathogenesis of ADHD. The transmission difference between parents raises the possibility that an epigenetic process may be involved.

Stage 2 of the Wellcome Trust UK-Irish bipolar affective disorder sibling-pair genome screen: evidence for linkage on chromosomes 6q16-q21, 4q12-q21, 9p21, 10p14-p12 and 18q22

Bipolar affective disorder (BPAD) is a common psychiatric disorder with complex genetic aetiology. We have undertaken a genome-wide scan in one of the largest samples of bipolar affected sibling pairs (ASPs) using a two-stage approach combining sample splitting and marker grid tightening. In this second stage analysis, we have examined 17 regions that achieved a nominally significant maximum likelihood LOD score (MLS) threshold of 0.74 (or 1.18 for the X-chromosome) in stage one. The second stage has added 135 ASP families to bring the total stage 2 sample to 395 ASPs. In total, 494 microsatellite markers have been used to screen the human genome at a density of 10 cM in the first stage sample (260 ASPs) and 5 cM in the second stage. Under the broad diagnostic model, two markers gave LOD scores exceeding 3 with two-point analysis: D4S392 (LOD=3.30) and D10S197 (LOD=3.18). Multipoint analysis demonstrated suggestive evidence of linkage between BPAD and chromosomal regions 6q16-q21 (MLS=2.61) and 4q12-q21 (MLS=2.38). 6q16-q21 is of particular interest because our data, together with those from two recent genome scans, make this the best supported linkage region in BPAD. Further, our data show evidence of a gender effect at this locus with increased sharing predominantly within the male-male pairs. Our scan also provides support for linkage (MLS> or =1.5) at several other regions that have been implicated in meta-analyses of bipolar disorder and/or schizophrenia including 9p21, 10p14-p12 and 18q22.

Exhaled nitric oxide levels during acute asthma exacerbation

OBJECTIVES

Fractional exhaled nitric oxide (FE(NO)) has been shown in laboratory settings and trials of patients with stable asthma to correlate with the degree of airway inflammation. The authors hypothesized that the technique of measuring FE(NO) would be reproducible in the setting of acute asthma in the emergency department (ED) and that the FE(NO) results during ED visits would potentially predict disposition, predict relapse following discharge, and correlate with the National Institutes of Health (NIH) asthma severity scale and peak expiratory flow measurements.

METHODS

The authors prospectively measured FE(NO) in a convenience sample of ED patients with acute exacerbations of asthma, both at the earliest possible opportunity and then one hour later. Each assessment point included triplicate measurements to assess reproducibility. The authors also performed spirometry and classified asthma severity using the NIH asthma severity scale. Discharged patients were contacted in 72 hours to determine whether their asthma had relapsed.

RESULTS

The authors discontinued the trial (n = 53) after a planned interim analysis demonstrated reproducibility (coefficient of variation, 15%) substantially worse than our a priori threshold for precision (4%). There was no association between FE(NO) response and corresponding changes in spirometry or clinical scores. Areas under the receiver operating characteristic curves for the prediction of hospitalization and relapse were poor (0.579 and 0.713, respectively).

CONCLUSIONS

FE(NO) measurements in ED patients with acute asthma exacerbations were poorly reproducible and did not correlate with standard measures of asthma severity. These results suggest that using existing technology, FE(NO) is not a useful marker for assessing severity, response to treatment, or disposition of acute asthmatic patients in the ED.

Health co-morbidities in ageing persons with Down syndrome and Alzheimer's dementia

BACKGROUND

Consideration of the relationship between physical and mental health co-morbidities in ageing persons with Down syndrome (DS) and Alzheimer's dementia (AD) is of clinical importance both from a care and resource perspective. AIM To investigate and measure health co-morbidities in ageing persons with Down syndrome with and without AD.

METHODS

Recorded physical and mental health needs were ascertained for 124 persons with DS>35 years through a systematic and detailed search of individual medical and nursing case records. Differences in persons with and without AD were investigated, by stage of dementia and by level of intellectual disability (ID). A summed score for health co-morbidities was created and compared using t-tests.

RESULTS

Persons with AD had significantly higher co-morbidity scores than persons without AD (t=-8.992, d.f.=121, P<0.0001). There was also a significant difference in summed co-morbidity scores for persons at end-stage vs. persons at mid-stage AD (t=-6.429, d.f.=56, P<0.0001). No differences were found by level of ID.

CONCLUSIONS

Increasing health co-morbidities in persons with DS and AD have important implications for care and resources. Appropriate environmental supports combined with competent skilled staff are crucial and will have an important impact on the quality of life for this increasingly at risk population.

Serotonin transporter gene and autism: a haplotype analysis in an Irish autistic population

The role of the serotonin transporter (5-HTT) in the development of neuropsychiatric disorders has been widely investigated. Two polymorphisms, an insertion/deletion in the promoter region and a 12 repeat allele in a variable nucleotide tandem repeat (VNTR) in intron 2, drive higher expression of the 5-HTT gene. Four studies have shown nominally significant excess transmission of alleles of the 5-HTT gene in autism, while three studies have reported no excess transmission. This present study investigates the role of 5-HTT in the genetically homogenous Irish population. In all, 84 families were genotyped for five polymorphisms (three SNPs, a VNTR and an in/del). The analysis of allele transmissions using the transmission disequilibrium test (TDT) was undertaken and indicated preferential transmission of the short promoter allele (TDT P-value=0.0334). Linkage disequilibrium between markers was calculated and haplotypes were assessed for excess transmission and odds ratios (ORs) to affected children. A number of haplotypes, especially those involving and surrounding SNP10, showed evidence of association. The ORs ranged from 1.2 to 2.4. The most significant haplotype associated with transmission to affected probands was the SNP10-VNTR-SNP18 haplotype (chi(2)=7.3023, P=0.0069, odds ratio=1.8). This haplotype included the 12 repeat allele of the VNTR, which is associated with increased expression and may play a subtle role in the early development of the brain in affected probands.

Identification in 2 Independent Samples of a Novel Schizophrenia RiskHaplotype of the Dystrobrevin Binding Protein Gene (DTNBP1)

CONTEXT

Recent research suggests that variation in the gene encoding dystrobrevin binding protein (DTNBP1) confers susceptibility to schizophrenia. Thus far, no specific risk haplotype has been identified in more than 1 study.

OBJECTIVES

To confirm DTNBP1 as a schizophrenia susceptibility gene, to identify and replicate specific risk and protective haplotypes, and to explore relationships between DTNBP1 and the phenotype.

DESIGN

Genetic association study based on mutation detection and case-control analysis.

SETTING

All subjects were unrelated and ascertained from general (secondary care) psychiatric inpatient and outpatient services.

PARTICIPANTS

The Cardiff, Wales, sample included 708 white subjects from the United Kingdom and Ireland (221 females) who met DSM-IV criteria for schizophrenia and were individually matched for age, sex, and ethnicity to 711 blood donor controls (233 females). Mean +/- SD age at first psychiatric contact for cases was 23.6 +/- 7.7 years; mean age at ascertainment was 41.8 +/- 13.5 years. The Dublin, Ireland, sample included 219 white subjects from the Republic of Ireland who met DSM-III-R criteria for schizophrenia or schizoaffective disorder and 231 controls. The mean age of the Irish cases was 46.0 +/- 8.5 years; mean age at first psychiatric contact was 25.2 +/- 12.4 years.

MAIN OUTCOME MEASURE

Evidence for association between the DTNBP1 locus and schizophrenia.

RESULTS

In the Cardiff sample, there was no evidence for association with previously implicated haplotypes but strong evidence for association with multiple novel haplotypes. Maximum evidence was found for a novel 3-marker haplotype (global P<.001), composed of 1 risk haplotype (P =.01) and 2 protective haplotypes, 1 common (P =.006) and 1 rare (P<.001). Specific risk and protective haplotypes were replicated in the Dublin sample (P =.02,.047, and.006, respectively). The only phenotypic variable associated with any haplotype was between the common protective haplotype and higher educational achievement (P =.02, corrected for multiple tests).

CONCLUSIONS

DTNBP1 is a susceptibility gene for schizophrenia. Specific risk and protective haplotypes were identified and replicated. Association with educational achievement may suggest protection mediated by IQ, although this needs to be confirmed in an independent data set.

Confirmation and refinement of an 'at-risk' haplotype for schizophrenia suggests the EST cluster, Hs.97362, as a potential susceptibility gene at the Neuregulin-1 locus

Two recent association studies have implicated the neuregulin-1 gene (NRG1) at chromosome 8p21-22 as a susceptibility gene for schizophrenia. Stefansson et al identified three 'at-risk' haplotypes (HapA, B and C) which spanned the NRG1 locus and shared a common core haplotype. Subsequently, they demonstrated evidence that the core haplotype was associated with schizophrenia in an independent Scottish sample. To confirm and refine this haplotype we investigated the NRG1 locus in an independent Irish case-control sample. We did not find the core haplotype to be associated in our sample. However, we identified a refined 2-marker haplotype (HapB(IRE)) that shared common alleles with one of the Icelandic 'at-risk' haplotypes and is in significant excess in the Irish cases (19.4%) vs controls (12.3%) (P=0.013). This refined 'at-risk' haplotype is also in significant excess in the Scottish case sample (17.0% vs 13.5%; P=0.036). Interestingly, this refined 'at-risk' haplotype is positioned close to an EST cluster of unknown function (Hs.97362) within intron 1 of NRG1.

Identification of a recurrent mutation in the CYLD gene in Brooke-Spiegler syndrome

Brooke-Spiegler syndrome is an autosomal dominantly inherited disease with predisposition to neoplasms of the skin appendages. The disease has been mapped to 16q, and mutations in the CYLD gene have been identified in families with this disorder. We describe an individual with BSS exhibiting clinical heterogeneity in which a heterozygous frameshift mutation in CYLD, 2172delA, has been identified. These findings extend the body of evidence that mutations in CYLD are involved in Brooke-Spiegler syndrome and provide additional information for phenotype-genotype correlation.

Late onset Alzheimer's disease and apolipoprotein association in the Irish population: relative risk and attributable fraction

BACKGROUND

Familial and sporadic late onset Alzheimer's disease (LOAD) shows a consistent genetic association with APOE epsilon4.

AIMS

To examine the role of APOE in the AD Irish population.

METHODS

One hundred and ten Irish LOAD patients and 217 ethnically-matched controls were genotyped for APOE marker as described by Crook et al. Chi square test was used to compare allelic and genotypic frequencies between patients and controls samples. Attributable fractions were calculated as described by Levin.

RESULTS

A highly significant association between AD and APOE epsilon4 was observed (chi2=37.9, p=0.0000000, RR=2.18). Further, the influence of APOEepsilon4 seems to follow a dose-dependent manner whereby individuals with the genotype APOEepsilon4/4 have a higher relative risk than those heterozygous for the epsilon4 allele (RR=4.03 and 1.76 respectively). The relative risk and the attributable fraction calculated for APOE epsilon4 are consistent with those reported for other European populations. This places the influence of this locus on AD development in the Irish population between those of the Spanish and New York white populations.

CONCLUSION

These findings provide further evidence for the importance of APOE in the development of AD.

Linkage disequilibrium mapping at DAT1, DRD5 and DBH narrows the search for ADHD susceptibility alleles at these loci

Abnormalities in dopaminergic neurotransmission are now accepted as factors in predisposing to ADHD. Evidence of associations between dopamine transporter gene polymorphism and ADHD was first reported by Cook et al. We confirmed the DAT1 association and also identified two additional susceptibility loci at the DRD5 and DBH. Notably, none of the associated variants at these three genes are known to be expressed. Other variants within or closely mapped to the associated alleles are likely to be relevant. In this investigation, we analyse additional markers creating a high-density map across and flanking these genes, and measure intermarker linkage disequilibrium (LD). None of the newly examined markers were more strongly associated with ADHD. At DAT1, the pattern of intermarker LD and haplotype association with the phenotype between exon 9 and the 3' of the gene suggests that the functional variant at DAT1 may be located to this region. For DRD5, three markers, covering a region of approximately 68 kb including the single DRD5 exon are all associated with disease, and thus do not provide localizing information. However, the data for DBH point to a region close to the centre of the gene. Correlation between D' and physical distance was observed between markers at DAT1 and DRD5 for distances less than 50 kb. This was not the case for DBH, where LD breakdown was observed between the intron 5 and intron 9 polymorphisms although they are only 9 kb apart. Further genetic analysis is unlikely to refine the location of susceptibility variants and functional assessment of variants within associated regions is required.

Serotonergic system and attention deficit hyperactivity disorder (ADHD): a potential susceptibility locus at the 5-HT(1B) receptor gene in 273 nuclear families from a multi-centre sample

Attention deficit hyperactivity disorder (ADHD) is a highly heritable and heterogeneous disorder, which usually becomes apparent during the first few years of childhood. Imbalance in dopamine neurotransmission has been suggested as a factor predisposing to ADHD. However, evidence has suggested an interaction between dopamine and serotonin systems in the pathophysiology of the disorder. Studies using selective agonists of the different 5-HT receptors microinjected into selected brain structures have shown a positive modulating effect on the functional activities of the mesotelencephalic dopaminergic system. This suggests that some of the genetic predisposition to ADHD might be due to DNA variation at serotonin system genes. In this study, we investigated polymorphisms in HTR(1B) and HTR(2A) (which encode the serotonin receptors 5-HT(1B) and 5-HT(2A) respectively) in a European ADHD sample. Using haplotype based haplotype relative risk (HHRR) and transmission disequilibrium test (TDT) analyses, we observed significant preferential transmission of the allele 861G of the HTR(1B) in the total sample (for HHRR; chi(2) = 7.4, P = 0.0065 and TDT; (chi(2) = 6.4, P = 0.014). Analysis of HTR(2A) failed to reveal evidence of association or linkage between the His452Tyr polymorphism and ADHD in the total sample. However, a significantly increased transmission of the allele 452His was observed in the Irish sample alone (chi(2) = 4.9, P = 0.026). These preliminary data suggest an important role for the serotonin system in the development of ADHD. Further studies, preferentially including different ethnic groups are required to substantiate these findings.

Evidence that variation at the serotonin transporter gene influences susceptibility to attention deficit hyperactivity disorder (ADHD): analysis and pooled analysis

Reduced central serotonergic activity has been implicated in poor impulse regulation and aggressive behaviour in animals, adults and also young children.(1,2) Two recently published studies have implicated variation at a polymorphism in the promoter of the serotonin transporter (5HTT; hSERT) in influencing susceptibility to ADHD.(3,4) Consistent with these results we have also found a trend for the long allele of the promoter polymorphism to influence susceptibility to ADHD in a sample of 113 ADHD parent proband trios (65 transmissions vs 49 non-transmissions, chi(2) = 2.25, P = 0.13). A pooled analysis of our, and these published results demonstrated a significant over representation of the long allele of the promoter in ADHD probands compared to controls (chi(2) = 7.14, P = 0.008). We have also examined two other 5HTT polymorphisms (the VNTR in intron 2 and the 3' UTR SNP). TDT analysis demonstrated preferential transmission of the T allele of the 3' UTR SNP (chi(2) = 4.06, P = 0.04). In addition, ETDT analysis of haplotypes demonstrated significant preferential transmission of haplotypes containing the T allele of the 3' UTR SNP with the long allele of the promoter polymorphism (chi(2) = 13.18, 3 df, P = 0.004) and the 10 repeat of the VNTR (chi(2) = 8.77, 3 df, P = 0.03). This study provides further evidence for the possible involvement of the serotonin transporter in susceptibility to ADHD.

Synaptosomal-associated protein 25 (SNAP-25) and attention deficit hyperactivity disorder (ADHD): evidence of linkage and association in the Irish population

Several lines of evidence have suggested that ADHD is a polygenic disorder produced by the interaction of several genes each of a minor effect. Synaptosomal-associated protein 25 (SNAP-25) is a presynaptic plasma membrane protein which is expressed highly and specifically in the nerve cells. The gene encodes a protein essential for synaptic vesicle fusion and neurotransmitter release. Animal model studies showed that the coloboma mouse mutant has a hyperactive phenotype similar to that of ADHD. The hyperactive phenotype of this model has been shown to be the result of a deletion of the SNAP-25 gene. DNA variations within or closely mapped to the SNAP-25 gene may alter the level of expression and hence may have an effect on the function of synaptic vesicle fusion and neurotransmitter release. Using HHRR and TDT we analysed 93 ADHD nuclear families from Ireland and found increased preferential transmission of SNAP-25/DdeI allelel to ADHD cases; HHRR (chi(2) = 6.55, P = 0.01) and linkage (TDT) (chi(2) = 6.5, P = 0.015). In contrast to our findings, Barr et al(1) reported an increased transmission of allele 2 of the DdeI polymorphism though this was not statistically significant. However, they also reported a significantly increased transmission of a haplotype (made of allele 1 of MnlI and allele 2 of the DdeI) in their Canadian ADHD sample. It is not clear what the role of SNAP-25 in ADHD is until these findings are either confirmed or refuted in other ADHD samples.

Paget's disease in New Zealand: evidence for declining prevalence

The prevalence rate of Paget's disease in New Zealand is believed to be among the highest in the world, but recent data suggest that it may have decreased in recent decades. We estimated the current prevalence of Paget's disease in subjects of European origin (>55 years of age) in two New Zealand cities (Dunedin and Auckland) based on review of nearly 2000 pelvic radiographs. Prevalence rate increased with age (p = 0.022) and was higher in men (p = 0.014), but there was no significant difference between the two cities. The Dunedin data were compared with a 1983 survey from the same city, and prevalence was approximately half its previous level (p = 0.012). In Auckland, the prevalence of an isolated raised plasma alkaline phosphatase level (>150 U/L, normal range <120 U/L) was estimated in over 80,000 blood samples processed at a community laboratory. The prevalence of "biochemical Paget's disease," as assessed by this surrogate marker, was very similar to that observed in the radiographic survey in Auckland for subjects <80 years of age, but not for older subjects. We conclude that the prevalence of Paget's disease in New Zealand has declined over the past two decades, indicating that there are important environmental determinants in its development. Biochemical estimates of the prevalence of Paget's disease agree well with radiographic estimates, except in the elderly. The method used herein offers an alternative way of determining the prevalence of Paget's disease.

A pilot study of the reliability and validity of the Caregiver Activity Survey - Intellectual Disability (CAS-ID)

BACKGROUND

People with Down's syndrome (DS) are at increased risk of Alzheimer-type dementia (AD) when compared to the general population. Despite AD being a serious progressive disorder, little attention has been paid to the impact of the illness on formal caregivers. In the general population, the Caregiver Activity Survey (CAS) is used to measure time spent by family caregivers assisting people with AD in their day-to-day activities of living. In order to plan appropriate models of health and social care effectively for people with AD and DS, it is imperative that the care requirements of individuals at different stages of dementia are realized. An amended version of this survey, the Caregiver Activity Survey - Intellectual Disability (CAS-ID), was developed and tested for use by professional caregivers in the present study.

METHODS

The CAS-ID was administered to 30 people with DS and their caregivers. Convergent validity was tested by comparing the results of the CAS-ID to other validated tests for cognitive and functional impairment in individuals with DS. Test-retest and inter-rater reliability were investigated.

RESULTS

The final version of the CAS-ID consists of eight items: dressing, bathing/showering, grooming, toileting, eating and drinking, housekeeping, nursing care-related activities, and supervision/ behaviour management. The scale had excellent test-retest reliability, and correlated strongly with the Down Syndrome Mental Status Examination (DSMSE; r = -0.770), the Test for Severe Impairment (TSI; r = -0.881) and the Daily Living Skills Questionnaire (DLSQ; r = -0.855).

CONCLUSIONS

The present authors provide preliminary evidence for the validity and reliability of the CAS-ID. This instrument offers a means of identifying and measuring care and resources requirements as this population experiences symptoms of dementia. Such information may help assist healthcare professionals in planning supports and services to address the care challenges evidenced at different stages of the disease process.

The Wellcome trust UK-Irish bipolar affective disorder sibling-pair genome screen: first stage report

We have completed the first stage of a two-stage genome wide screen designed to identify chromosomal regions that may harbour susceptibility genes for bipolar affective disorder. The first stage screening sample included 509 subjects from 151 nuclear families recruited within the United Kingdom and Republic of Ireland. This sample contained 154 narrowly defined affected sibling pairs (DSM-IV BPI) and 258 broadly defined affected sibling pairs (DSM-IV BPI, SABP, BPII, BPNOS or MDD(R)), approximately two thirds of all families contained at least one other additional typed individual. All individuals were genotyped using 398 highly polymorphic microsatellite markers from Applied Biosystems's Linkage Mapping Set Version 2. The average inter-marker distance was 9.6 cM and the mean heterozygosity was 0.78. Analysis of these data using non-parametric linkage methods (MAPMAKER/SIBS) found no evidence for loci of major effect and no regions reached genome-wide significance for either suggestive or significant linkage. We identified 19 points across the genome where the MLS exceeded a value set for follow up in our second stage screen (MLS > or = 0.74 (equivalent to a nominal pointwise significance of 5%) under the narrowest diagnostic model). These points were on chromosomes 2, 3, 4, 6, 7, 9, 10, 12, 17, 18 & X. Some of these points overlapped with previous linkage reports both within bipolar affective disorder and other psychiatric illnesses. Under the narrowest diagnostic model, the single most significant multipoint linkage was on chromosome 18 at marker D18S452 (MLS=1.54). Overall the highest MLS was 1.70 on chromosome 2 at marker D2S125, under the broadest diagnostic model.

Pigments of Fungi. LXIX. Total Synthesis of (R)-Ochratoxin α and the Formal Total Synthesis of Ochratoxin

(R)-Ochratoxin α, the monochiral carboxylic acid component of the biologically active dipeptide ochratoxin A, is synthesized for the first time over nine steps from (R)-propylene oxide. The method constitutes a versatile and general route to functionalized dihydroisocoumarins.

Cloned genomic DNA of type 2 porcine circovirus is infectious when injected directly into the liver and lymph nodes of pigs: characterization of clinical disease, virus distribution, and pathologic lesions

Infection of animals with a molecular viral clone is critical to study the genetic determinants of viral replication and virulence in the host. Type 2 porcine circovirus (PCV2) has been incriminated as the cause of postweaning multisystemic wasting syndrome (PMWS), an emerging disease in pigs. We report here for the first time the construction and use of an infectious molecular DNA clone of PCV2 to characterize the disease and pathologic lesions associated with PCV2 infection by direct in vivo transfection of pigs with the molecular clone. The PCV2 molecular clone was generated by ligating two copies of the complete PCV2 genome in tandem into the pBluescript SK (pSK) vector and was shown to be infectious in vitro when transfected into PK-15 cells. Forty specific-pathogen-free pigs at 4 weeks of age were randomly assigned to four groups of 10 each. Group 1 pigs served as uninoculated controls. Pigs in group 2 were each inoculated intranasally with about 1.9 x 10(5) 50% tissue culture infective doses of a homogeneous PCV2 live virus stock derived from the molecular clone. Pigs in group 3 were each injected intrahepatically with 200 microg of the cloned PCV2 plasmid DNA, and pigs in group 4 were each injected into the superficial iliac lymph nodes with 200 microg of the cloned PCV2 plasmid DNA. Animals injected with the cloned PCV2 plasmid DNA developed infection resembling that induced by intranasal inoculation with PCV2 live virus stock. Seroconversion to PCV2-specific antibody was detected in the majority of pigs from the three inoculated groups at 35 days postinoculation (DPI). Viremia, beginning at 14 DPI and lasting 2 to 4 weeks, was detected in the majority of the pigs from all three inoculated groups. There were no remarkable clinical signs of PMWS in control or any of the inoculated pigs. Gross lesions in pigs of the three inoculated groups were similar and were characterized by systemically enlarged, tan lymph nodes and lungs that failed to collapse. Histopathological lesions and PCV2-specific antigen were detected in numerous tissues and organs, including brain, lung, heart, kidney, tonsil, lymph nodes, spleen, ileum, and liver of infected pigs. This study more definitively characterizes the clinical course and pathologic lesions exclusively attributable to PCV2 infection. The data from this study indicate that the cloned PCV2 genomic DNA may replace infectious virus for future PCV2 pathogenesis and immunization studies. The data also suggest that PCV2, although essential for development of PMWS, may require other factors or agents to induce the full spectrum of clinical signs and lesions associated with advanced cases of PMWS.

Sibling pairs with affective disorders: resemblance of demographic and clinical features

BACKGROUND

As part of a collaborative linkage study, the authors obtained clinical and demographic data on 160 families in which more than one sibling was affected with a bipolar illness. The aim of the study was to identify clinical characteristics that had a high degree of familiality.

METHOD

Data on age at onset, gender, frequency of illness-episodes and proportion of manic to depressive episodes were examined to determine intra-pair correlations in affected sibling pairs. Dimension scales were developed measuring frequency and severity of lifetime mania, depression, psychosis and mood-incongruence of psychotic symptoms; degree of familial aggregation for scores on these dimensions was calculated.

RESULTS

Sibling pairs correlated significantly for age at onset (p = 0.293, P < 0 001); dimension scores for psychosis (p = 0.332, P < 0.001); and proportion of manic to depressive episodes (p = 0.184, P = 0.002). These findings remained significant when correcting for multiple testing. Of the other test variables; mania (p = 0.171, P = 0.019); incongruence dimensions (p = 0.242, P = 0.042); .frequency of manic episodes (p = 0.152, P = 0.033); and frequency of depressive episodes (p = 0.155, P = 0.028) were associated with modest correlations but these were not significant after correction. Degree of familial aggregation was not significant for sex (kappa = 0.084) or dimension scores for depression (p = 0.078, P = 0.300).

CONCLUSIONS

Significant but modest familial resemblance has been shown for some specific features of bipolar illness, particularly age at onset and degree of psychosis. Further research may establish the extent to which these findings are mediated by genetic and/or environmental factors.

No association between CHRNA7 microsatellite markers and attention-deficit hyperactivity disorder

Attention-deficit hyperactivity disorder (ADHD) is a highly heritable, common psychiatric disorder of childhood that probably involves several genes. There are several lines of evidence suggesting that the nicotinic system may be functionally significant in ADHD. First, nicotine promotes the release of dopamine and has been shown to improve attention in adults with ADHD, smokers, and nonsmokers. Second, ADHD is a significant risk factor for early initiation of cigarette smoking in children and maternal cigarette smoking appears to be a risk factor for ADHD. Finally, animal studies in rats and monkeys also suggest that nicotine may be involved in attentional systems and locomotor activity. The nicotinic system has previously been studied in schizophrenia where the neuronal nicotinic acetylcholine receptor alpha 7 subunit gene (CHRNA7) has been implicated in decreased P50 inhibition and attentional disturbances in patients with schizophrenia and in many of their nonschizophrenic relatives. Three known microsatellite markers (D15S165, D15S1043, and D15S1360) near the nicotinic acetylcholine alpha 7 receptor gene, CHRNA7, were studied in 206 ADHD parent-proband trios of children aged 5-16 with ADHD according to DSM-IV criteria. Children with known major medical or psychiatric conditions or mental retardation (IQ < 70) were excluded from the study. Markers D15S165 and D15S1360 were in linkage disequilibrium. The extended Transmission Disequilibrium Test analyses demonstrated no evidence that variation at the microsatellite markers D15S1360, D15S1043, and D15S165 influences susceptibility to ADHD. However, it remains possible that the CHRNA7 gene and other nicotinic system genes may be involved in conferring susceptibility to ADHD.