A study of the PEMT gene in schizophrenia
ABSTRACT The phospholipid hypothesis of schizophrenia is becoming popular because of the findings from the niacin flush test, the treatment with polyunsaturated fatty acids (PUFAs), biochemical studies for the phospholipid metabolism pathway and genetic studies of phospholipase A2. The present study attempted to investigate the gene coding for phosphatidylethanolamine N-methyltransferase (PEMT), which is an important enzyme for the synthesis of membrane phospholipids. We recruited 271 Chinese parent-offspring trios of Han descent and detected 3 single nucleotide polymorphisms (SNPs) at the PEMT locus. The transmission disequilibrium test (TDT) showed allelic association for rs464396 (X2 = 9.4, P = 0.002), but not for the other two. The 2-SNP haplotype analysis showed haplotypic association for both the rs936108-rs464396 haplotypes (X2 = 25.7, d.f. = 3, P = 0.00001) and the rs464396-rs4244593 haplotypes (X2 = 17.3, d.f. = 3, P = 0.0006). The 3-SNP haplotype analysis also showed a haplotypic association (X2 = 24.4, d.f. = 7, P = 0.0006). The present results suggest that the PEMT gene may contribute to the etiology of schizophrenia.
SourceAvailable from: Bernard J Crespi[Show abstract] [Hide abstract]
ABSTRACT: Genomic sister-disorders are defined here as diseases mediated by duplications versus deletions of the same region. Such disorders can provide unique information concerning the genomic underpinnings of human neurodevelopment because effects of diametric variation in gene copy number on cognitive and behavioral phenotypes can be inferred. We describe evidence from the literature on deletions versus duplications for the regions underlying the best-known human neurogenetic sister-disorders, including Williams syndrome, Velocardiofacial syndrome, and Smith–Magenis syndrome, as well as the X-chromosomal conditions Klinefelter and Turner syndromes. These data suggest that diametric copy-number alterations can, like diametric alterations to imprinted genes, generate contrasting phenotypes associated with autistic-spectrum and psychotic-spectrum conditions. Genomically based perturbations to the development of the human social brain are thus apparently mediated to a notable degree by effects of variation in gene copy number. We also conducted the first analyses of positive selection for genes in the regions affected by these disorders. We found evidence consistent with adaptive evolution of protein-coding genes, or selective sweeps, for three of the four sets of sister-syndromes analyzed. These studies of selection facilitate identification of candidate genes for the phenotypes observed and lend a novel evolutionary dimension to the analysis of human cognitive architecture and neurogenetic disorders.Evolutionary Applications 01/2009; 2(1):81 - 100. DOI:10.1111/j.1752-4571.2008.00056.x · 4.57 Impact Factor
[Show abstract] [Hide abstract]
ABSTRACT: The hippocampal formation plays a critical role in cognitive function. The developmental events that shape the hippocampal formation are continuing to be elucidated and their implications for brain function are emerging as well as applying those advances to interventions that have important possibilities for the treatment of brain dysfunction. The story told in this chapter is about the use of the in oculo transplant method to illuminate intrinsic and extrinsic features that underlie the development of the dentate gyrus and adjacent hippocampus and the role of one molecule in the hippocampus and schizophrenia. Schizophrenia, originally conceptualized as a dysfunction in dopaminergic neurotransmission, is now known to involve multiple neuronal systems. Dysfunction of hippocampal neurons is emerging as one of its signature pathological features. Basic insights into the development and function of hippocampal interneurons form the basis of a new treatment initiative for this illness. Evidence for the role of the alpha 7-nicotinic acetylcholine receptor in the development and function of these neurons in rodents has led to human trials of nicotinic agonists for cognitive dysfunction in schizophrenia and the possibility of improving hippocampal development in children at risk for schizophrenia by perinatal supplementation with choline, which can act as an alpha 7-nicotinic acetylcholine receptor agonist.Progress in Neurobiology 02/2010; DOI:10.1016/j.pneurobio.2009.10.008 · 10.30 Impact Factor
[Show abstract] [Hide abstract]
ABSTRACT: OBJECTIVE Deficient cerebral inhibition is a pathophysiological brain deficit related to poor sensory gating and attention in schizophrenia and other disorders. Cerebral inhibition develops perinatally, influenced by genetic and in utero factors. Amniotic choline activates fetal α7-nicotinic acetylcholine receptors and facilitates development of cerebral inhibition. Increasing this activation may protect infants from future illness by promoting normal brain development. The authors investigated the effects of perinatal choline supplementation on the development of cerebral inhibition in human infants. METHOD A randomized placebo-controlled clinical trial of dietary phosphatidylcholine supplementation was conducted with 100 healthy pregnant women, starting in the second trimester. Supplementation to twice normal dietary levels for mother or newborn continued through the third postnatal month. All women received dietary advice regardless of treatment. Infants' electrophysiological recordings of inhibition of the P50 component of the cerebral evoked response to paired sounds were analyzed. The criterion for inhibition was suppression of the amplitude of the second P50 response by at least half, compared with the first response. RESULTS No adverse effects of choline were observed in maternal health and delivery, birth, or infant development. At the fifth postnatal week, the P50 response was suppressed in more choline-treated infants (76%) compared with placebo-treated infants (43%) (effect size=0.7). There was no difference at the 13th week. A CHRNA7 genotype associated with schizophrenia was correlated with diminished P50 inhibition in the placebo-treated infants, but not in the choline-treated infants. CONCLUSIONS Neonatal developmental delay in inhibition is associated with attentional problems as the child matures. Perinatal choline activates timely development of cerebral inhibition, even in the presence of gene mutations that otherwise delay it.American Journal of Psychiatry 01/2013; DOI:10.1176/appi.ajp.2012.12070940 · 13.56 Impact Factor