Christian R. Andres

Recurrent Rearrangements in Synaptic and Neurodevelopmental Genes and Shared Biologic Pathways in Schizophrenia, Autism, and Mental Retardation

CONTEXT Results of comparative genomic hybridization studies have suggested that rare copy number variations (CNVs) at numerous loci are involved in the cause of mental retardation, autism spectrum disorders, and schizophrenia. OBJECTIVES To provide an estimate of the collective frequency of a set of recurrent or overlapping CNVs in 3 different groups of cases compared with healthy control subjects and to assess whether each CNV is present in more than 1 clinical category. DESIGN Case-control study. SETTING Academic research. PARTICIPANTS We investigated 28 candidate loci previously identified by comparative genomic hybridization studies for gene dosage alteration in 247 cases with mental retardation, in 260 cases with autism spectrum disorders, in 236 cases with schizophrenia or schizoaffective disorder, and in 236 controls. MAIN OUTCOME MEASURES Collective and individual frequencies of the analyzed CNVs in cases compared with controls. RESULTS Recurrent or overlapping CNVs were found in cases at 39.3% of the selected loci. The collective frequency of CNVs at these loci is significantly increased in cases with autism, in cases with schizophrenia, and in cases with mental retardation compared with controls (P < .001, P = .01, and P = .001, respectively, Fisher exact test). Individual significance (P = .02 without correction for multiple testing) was reached for the association between autism and a 350-kilobase deletion located at 22q11 and spanning the PRODH and DGCR6 genes. CONCLUSIONS Weakly to moderately recurrent CNVs (transmitted or occurring de novo) seem to be causative or contributory factors for these diseases. Most of these CNVs (which contain genes involved in neurotransmission or in synapse formation and maintenance) are present in the 3 pathologic conditions (schizophrenia, autism, and mental retardation), supporting the existence of shared biologic pathways in these neurodevelopmental disorders.

Maternal Exposure to LPS Induces Hypomyelination in the Internal Capsule and Programmed Cell Death in the Deep Gray Matter in Newborn Rats

Epidemiologic and experimental findings implicate maternal infection in the etiology of injury to brain white matter, which may lead to cerebral palsy in preterm newborns. In the present study, inflammation and brain damage in 1- and 7-d-old rats were investigated after maternal inflammation. Intraperitoneal injection of 300 μg/kg of Escherichia coli lipopolysaccharide was administered to pregnant Wistar rats at d 19 and 20 of gestation (LPS group). Control females received a saline injection. Proinflammatory cytokines IL-1β, tumor necrosis factor-α, and IL-6 expression in the fetal brain were determined by reverse transcription quantitative polymerase chain reaction. Brain injury was examined in 16-μm coronal brain sections by GFAP, MBP, caspase-3 immunohistochemistry, and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling. Expression of IL-1β was significantly increased 3 d after maternal administration (P1). A significant increase in cell death occurred at P1 and P7 in specific brain areas, i.e. in the subventricular striatal zone at P1, and in 1) the periventricular striatum, 2) the periventricular white matter, and 3) the germinative ventricular zone at P7. We also observed typical astrogliosis and strong hypomyelination in the external and internal capsule in the LPS group at P7. These results demonstrate that maternal LPS treatment induces persistent fetal inflammatory reactions associated with significant white matter injury in progeny at P1 and P7. This model should be relevant for the study of the pathophysiological mechanisms involved in cerebral white matter damage in preterm human newborns and in the development of therapeutic strategies.

Fetal exposure to teratogens: evidence of genes involved in autism.

Environmental challenges during the prenatal period can result in behavioral abnormalities and cognitive deficits that appear later in life such as autism. Prenatal exposure to valproic acid, ethanol, thalidomide and misoprostol has been shown to be associated with an increased incidence of autism. In addition, rodents exposed in utero to some of these drugs show autism-like abnormalities, including brain changes and lifelong behavior dysfunction. Our aim is to summarize current understanding of the relationship between in utero exposure to these drugs and autism in humans and in autism-like animal model phenotypes. It also highlights the importance of these models to understanding the neurobiology of autism, particularly in the identification of susceptibility genes. These drugs are able to modulate the expression of many genes involved in processes such as proliferation, apoptosis, neuronal differentiation and migration, synaptogenesis and synaptic activity. It seems essential to focus research on genes expressed during early neurodevelopment which may be the target of mutations or affected by drugs such as those included in this review.

Behavior and serotonergic disorders in rats exposed prenatally to valproate: A model for autism

In order to explore whether some aspects of the autistic phenotype could be related to impairment of the serotonergic system, we chose an animal model which mimics a potential cause of autism, i.e. rats exposed to valproate (VPA) on the 9th embryonic day (E9). Previous studies have suggested that VPA exposure in rats at E9 caused a dramatic shift in the distribution of serotonergic neurons on postnatal day 50 (PND50). Behavioral studies have also been performed but on rats that were exposed to VPA later (E12.5). Our aim was to test whether VPA exposure at E9 induces comparable behavioral impairments than at E12.5 and causes serotonergic impairments which could be related to behavioral modifications. The results showed significant behavioral impairments such as a lower tendency to initiate social interactions and hyperlocomotor activity in juvenile male rats. The serotonin levels of these animals at PND50 were decreased (-46%) in the hippocampus, a structure involved in social behavior. This study suggests that VPA could have a direct or indirect action on the serotonergic system as early as the progenitor cell stage. Early embryonic exposure to VPA in rats provides a good model for several specific aspects of autism and should help to continue to explore pathophysiological hypotheses.

What Was the Set of Ubiquitin and Ubiquitin-Like Conjugating Enzymes in the Eukaryote Common Ancestor?

Ubiquitin (Ub)-conjugating enzymes (E2) are key enzymes in ubiquitination or Ub-like modifications of proteins. We searched for all proteins belonging to the E2 enzyme super-family in seven species (Homo sapiens, Mus musculus, Drosophila melanogaster, Caenorhabditis elegans, Schizosaccharomyces pombe, Saccharomyces cerevisiae, and Arabidopsis thaliana) to identify families and to reconstruct each family’s phylogeny. Our phylogenetic analysis of 207 genes led us to define 17 E2 families, with 37 E2 genes, in the human genome. The subdivision of E2 into four classes did not correspond to the phylogenetic tree. The sequence signature HPN (histidine–proline–asparagine), followed by a tryptophan residue at 16 (up to 29) amino acids, was highly conserved. When present, the active cysteine was found 7 to 8 amino acids from the C-terminal end of HPN. The secondary structures were characterized by a canonical alpha/beta fold. Only family 10 deviated from the common organization because the proteins were devoid of enzymatic activity. Family 7 had an insertion between beta strands 1 and 2; families 3, 5 and 14 had an insertion between the active cysteine and the conserved tryptophan. The three-dimensional data of these proteins highlight a strong structural conservation of the core domain. Our analysis shows that the primitive eukaryote ancestor possessed a diversified set of E2 enzymes, thus emphasizing the importance of the Ub pathway. This comprehensive overview of E2 enzymes emphasizes the diversity and evolution of this superfamily and helps clarify the nomenclature and true orthologies. A better understanding of the functions of these enzymes is necessary to decipher several human diseases.

Renal impairment and ischemic stroke risk assessment in patients with atrial fibrillation: the Loire Valley Atrial Fibrillation Project.

OBJECTIVES This study sought to determine the risk of ischemic stroke (IS)/thromboembolism (TE) associated with renal impairment and its incremental predictive value over established risk stratification scores (congestive heart failure, hypertension, age ≥75 years, diabetes, previous stroke [CHADS2] and congestive heart failure, hypertension, age ≥75 years, diabetes, previous stroke, vascular disease, age 65 to 74 years, sex category (female) [CHA₂DS₂-VASc]) in patients with atrial fibrillation (AF). BACKGROUND Risk stratification schemes for prediction of IS/TE in patients with AF are validated but do not include renal impairment. METHODS Patients diagnosed with nonvalvular AF and available estimated glomerular filtration rate (eGFR) data in a 4-hospital institution between 2000 and 2010 were identified. The study population was stratified by renal impairment defined by serum creatinine level and by eGFR measured at time of diagnosis of AF. Independent risk factors of IS/TE (including renal impairment) were investigated in Cox regression models. The incremental predictive value of renal impairment over CHADS₂ and CHA₂DS₂-VASc were assessed with the c-statistic, net reclassification improvement, and integrated discrimination improvement. We focused on the 1-year outcomes in our analyses. RESULTS Of 8,962 eligible individuals, 5,912 (66%) had nonvalvular AF and available eGFR data. Renal impairment by both creatinine and eGFR definitions was associated with higher rates of IS/TE at 1 year, compared with normal renal function. After adjustment for CHADS₂ risk factors, renal impairment did not significantly increase the risk of IS/TE at 1 year (hazard ratio: 1.06; 95% confidence interval [CI]: 0.75 to 1.49 for renal impairment; and hazard ratio: 1.09; 95% CI: 0.84 to 1.41 for eGFR). When renal impairment was added to existing risk scoring systems for stroke/TE (CHADS₂ and CHA₂DS₂-VASc), it did not independently add to the predictive value of the scores, whether defined by serum creatinine level or eGFR. This was evident even when the analysis was confined to only those patients with at least 1 year of follow-up. CONCLUSIONS Renal impairment was not an independent predictor of IS/TE in patients with AF and did not significantly improve the predictive ability of the CHADS₂ or CHA₂DS₂-VASc scores.

SMN1 gene, but not SMN2, is a risk factor for sporadic ALS

Background: SMN1 gene deletions cause spinal muscular atrophy, and SMN2 gene deletions have been associated with sporadic lower motor neuron diseases. Objectives: To study the frequency of abnormal SMN1 gene copy numbers and to determine whether SMN2 gene modulates the risk of amyotrophic lateral sclerosis (ALS) or the duration of evolution. Method: The authors studied SMN1 and SMN2 genes in 600 patients with sporadic ALS and 621 controls using a quantitative PCR method. Results: The authors found an association of ALS with an abnormal copy number (one or three copies) of SMN1 gene (p < 0.0001) with an OR of 2.8 (1.8 to 4.4, 95% CI). There was no association with SMN2 copy numbers and no effect of SMN2 copies on the duration of evolution in ALS independently of SMN1 copy number. Conclusion: Abnormal SMN1 gene copy numbers are a genetic risk factor in sporadic amyotrophic lateral sclerosis. There was no modulator effect of the SMN2 gene.

A second heterozygous MDR3 nonsense mutation associated with intrahepatic cholestasis of pregnancy

Intrahepatic cholestasis of pregnancy (ICP, 147480) is a liver disorder unique to pregnancy, which usually manifests during late pregnancy and disappears spontaneously after delivery. Maternal symptoms are characterised by generalised pruritus with or without jaundice. The main biological features are increased serum alanine transaminase (ALT) activities and serum bile acid concentrations.1–3 Serum gamma-glutamyl transpeptidase (GGT) activity remains within normal limits or is increased.4,5 The occurrence of ICP carries a risk for the baby because of premature spontaneous delivery or sudden fetal death and pruritus may cause considerable discomfort for the mother.1–3,6 Cholestasis frequently recurs in subsequent pregnancies and rarely during administration of oral contraceptives.5 The cause of ICP is unknown. However, clinical and epidemiological studies suggest mainly hormonal and genetic factors.1–3,7 Genetic factors have been suggested by the existence of familial cases and by the high incidence of ICP in some ethnic groups, such as the Araucanos Indians of Chile.8 The multidrug resistance 3 ( MDR3 , ABCB4 , 171060) gene, localised on 7q21.1, was first reported to be involved in ICP by de Vree et al .9 In a large consanguineous family, subjects affected by a subtype of progressive familial intrahepatic cholestasis called PFIC3 were homozygous for a nonsense mutation in exon 23 (R957X) and women affected by ICP were heterozygous; in another family, the same authors reported a homozygous deletion of exon 6 (426-432del) in a PFIC3 patient with consanguineous, healthy parents.9 A mutation in exon 14 of MDR3 (1744delT) was identified in another large pedigree in which all PFIC patients were homozygous for the mutation and women with ICP were heterozygous.10,11 Dixon et al 12 investigated eight women affected by ICP with increased serum GGT activity and no familial history of PFIC. …

Malnutrition at the time of diagnosis is associated with a shorter disease duration in ALS

BACKGROUND Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease. During the course of the illness, malnutrition can occur and may shorten survival. The aim of our study was to determine whether clinical nutritional parameters that are used in daily practice are associated with prognosis and whether they can help guide therapeutic decisions. METHODS We retrospectively reviewed a cohort of ALS patients in our institution between January 2002 and January 2006. Clinical and demographic outcomes were compiled. To evaluate predictors of survival, we analyzed several clinical nutritional parameters available in daily practice (body mass index, weight loss exceeding 10% of premorbid weight at the time of diagnosis and during the course of the disease and the use of technical supports such as percutaneous endoscopic gastrostomy (PEG) and non-invasive ventilation). RESULTS Sixty-three patients were retrospectively studied. Thirteen patients had weight loss exceeding 10% of premorbid weight at the time of diagnosis and thirty patients had weight loss meeting this criterion at final examination. Weight loss exceeding 10% at the time of diagnosis was associated with a shorter duration of disease (17±6months versus 35±26months; p=0.002). A linear correlation was found between mean disease duration and time between onset and diagnosis (p<0.0001). The subgroup of patients with a PEG had a longer survival time than the other subgroup of patients (p=0.02). CONCLUSIONS In ALS patients, early and marked weight loss significantly predicts a worse prognosis. The percentage of premorbid weight loss is a suitable and useful measure that can be used in daily practice to identify patients with a poor prognosis.

Metabolomics in cerebrospinal fluid of patients with amyotrophic lateral sclerosis: an untargeted approach via high-resolution mass spectrometry.

Amyotrophic lateral sclerosis (ALS) is characterized by the absence of reliable diagnostic biomarkers. The aim of the study was to (i) devise an untargeted metabolomics methodology that reliably compares cerebrospinal fluid (CSF) from ALS patients and controls by liquid chromatography coupled to high-resolution mass spectrometry (LC-HRMS); (ii) ascertain a metabolic signature of ALS by use of the LC-HRMS platform; (iii) identify metabolites for use as diagnostic or pathophysiologic markers. We developed a method to analyze CSF components by UPLC coupled with a Q-Exactive mass spectrometer that uses electrospray ionization. Metabolomic profiles were created from the CSF obtained at diagnosis from ALS patients and patients with other neurological conditions. We performed multivariate analyses (OPLS-DA) and univariate analyses to assess the contribution of individual metabolites as well as compounds identified in other studies. Sixty-six CSF samples from ALS patients and 128 from controls were analyzed. Metabolome analysis correctly predicted the diagnosis of ALS in more than 80% of cases. OPLS-DA identified four features that discriminated diagnostic group (p < 0.004). Our data demonstrate that untargeted metabolomics with LC-HRMS is a robust procedure to generate a specific metabolic profile for ALS from CSF and could be an important aid to the development of biomarkers for the disease.