SSCP primer design based on single-strand DNA structure predicted by a DNA folding program

To predict alterations in single-strand DNA mobility in non-denaturing electrophoretic gels, Zuker's RNA folding program was modified. Energy files utilized by the LRNA RNA folding algorithm were modified to emulate folding of single-strand DNA. Energy files were modified to disallow G-T base pairing. Stacking energies were corrected for DNA thermodynamics. Constraints on loop nucleotide sequences were removed. The LRNA RNA folding algorithm using the DNA fold energy files was applied to predict folding of PCR generated single-strand DNA molecules from polymorphic human ALDH2 and TPH alleles. The DNA-Fold version 1.0 program was used to design primers to create and abolish SSCP mobility shifts. Primers were made that add a 5' tag sequence or alter complementarity to an internal sequence. Differences in DNA secondary structure were assessed by SSCP analysis and compared to single-strand DNA secondary structure predictions. Results demonstrate that alterations in single-strand DNA conformation may be predicted using DNA-Fold 1.0.

DRD4 dopamine receptor genotype and CSF monoamine metabolites in Finnish alcoholics and controls

The DRD4 dopamine receptor is thus far unique among neurotransmitter receptors in having a highly polymorphic gene structure that has been reported to produce altered receptor functioning. These allelic variations are caused by a 48-bp segment in exon III of the coding region which may be repeated from 2-10 times. Varying the numbers of repeated segments changes the length, structure, and, possibly, the functional efficiency of the receptor, which makes this gene an intriguing candidate for variations in dopamine-related behaviors, such as alcoholism and drug abuse. Thus far, these DRD4 alleles have been investigated for association with schizophrenia, bipolar disorder, Parkinson's disease, and chronic alcoholism, and all have been largely negative for a direct association. We evaluated the DRD4 genotype in 226 Finish adult males, 113 of whom were alcoholics, many of the early onset type with features of impulsivity and antisocial traits. Genotype frequencies were compared to 113 Finnish controls who were free of alcohol abuse, substance abuse, and major mental illness. In 70 alcoholics and 20 controls, we measured CSF homovanillic acid (HVA), the major metabolite of dopamine, and 5-hydroxyindoleacetic acid (5-HIAA). No association was found between a particular DRD4 dopamine receptor allele and alcoholism. CSF concentrations of the monoamine metabolites showed no significant difference among the DRD4 genotypes. This study of the DRD4 dopamine receptor in alcoholics is the first to be conducted in a clinically and ethnically homogeneous population and to relate the DRD4 genotype to CSF monoamine concentrations. The results indicate that there is no association of the DRD4 receptor with alcoholism.

Polymorphism and genetic mapping of the human oxytocin receptor gene on chromosome 3

Centrally administered oxytocin has been reported to facilitate affiliative and social behaviours, in functional harmony with its well-known peripheral effects on uterine contraction and milk ejection. The biological effects of oxytocin could be perturbed by mutations occurring in the sequence of the oxytocin receptor gene, and it would be of interest to establish the position of this gene on the human linkage map. Therefore we identified a polymorphism at the human oxytocin receptor gene. A portion of the 3' untranslated region containing a 30 bp CA repeat was amplified by polymerase chain reaction (PCR), revealing a polymorphism with two alleles occurring with frequencies of 0.77 and 0.23 in a sample of Caucasian CEPH parents (n = 70). The CA repeat polymorphism we detected was used to map the the human oxytocin receptor to chromosome 3p25-3p26, in a region which contains several important genes, including loci for Von Hippel-Lindau disease (VHL) and renal cell carcinoma.

Identification, expression, and pharmacology of a Cys23-Ser23 substitution in the human 5-HT2c receptor gene (HTR2C)

The function of brain serotonin-2C (5-HT2C) receptors, including behavioral and neurochemical responses to 5-HT2C agonist challenge, has been suggested to be abnormal in individuals with neuropsychiatric disorders. Thus, it is important to identify polymorphisms and functional variants within this gene. Using SSCP analysis, we identified a Cys23-Ser23 substitution (designated 5-HT2Ccys and 5-HT2Cser) in the first hydrophobic region of the human 5-HT2C receptor. Allele frequencies in unrelated Caucasians were 0.13 and 0.87 for 5-HT2Cser and 5-HT2Ccys, respectively. DNAs from informative CEPH families were typed for this polymorphism and analyzed with respect to 20 linked markers on the X chromosome. Linkage analysis placed the 5-HT2C receptor gene (HTR2C) on Xq24. To evaluate whether this amino acid substitution causes a variant function of this receptor, recombinant human 5-HT2Ccys and 5-HT2Cser receptors were expressed in Xenopus oocytes and tested for responses to 5-HT using electrophysiological techniques. Concentration-response curves for 5-HT were not significantly different in oocytes expressing either form of the receptor, suggesting that the 5-HT2Ccys and 5-HT2Cser receptor proteins may not differ in their responses to serotonin under baseline physiological conditions.

Two naturally occurring amino acid substitutions in the human 5-HT1A receptor: glycine 22 to serine 22 and isoleucine 28 to valine 28

The human 5-HT1A receptor was screened for naturally occurring mutations. The PCR product of the 5-HT1A receptor gene was digested with several restriction enzymes and evaluated by single-strand conformational polymorphism (SSCP) analysis. Comparison of the SSCP electrophoretic pattern with a restriction map of the 5-HT1A receptor allowed localization of the polymorphic sites facilitating their identification by sequence analysis. Two polymorphisms were identified in the human 5-HT1A receptor gene that altered amino acid composition. The polymorphisms encode amino acid substitutions in the 5-HT1A receptor of a glycine to serine at amino acid 22 and an isoleucine to valine at amino acid 28, respectively. Both polymorphisms alter the extracellular amino terminal domain of the 5-HT1A receptor. The polymorphic 5-HT1A alleles have been found in American and Finnish Caucasians and in native American Indians. This is the first report of a polymorphism in the human 5-HT1A receptor gene that alters the structure of the 5-HT1A receptor protein composition.

Mapping of the serotonin 5-HT1D beta autoreceptor gene on chromosome 6 and direct analysis for sequence variants

Abnormal brain serotonin function may be characteristic of several neuropsychiatric disorders. Thus, it is important to identify polymorphic genes and screen for functional variants at loci coding for genes that control normal serotonin functions. 5-HT1D beta is a terminal serotonin autoreceptor which may play a role in regulating serotonin synthesis and release. Using an SSCP technique we screened for 5-HT1D beta coding sequence variants in psychiatrically interviewed populations, which included controls, alcoholics, and alcoholic arsonists and alcoholic violent offenders with low CSF concentrations of the main serotonin metabolite 5-HIAA. A common polymorphism was identified in the 5-HT1D beta gene with allele frequencies of 0.72 and 0.28. The SSCP variant was caused by a silent G to C substitution at nucleotide 861 of the coding region. This polymorphism could also be detected as a HincII RFLP of amplified DNA. DNAs from informative CEPH families were typed for the HincII RFLP and analyzed with respect to 20 linked markers on chromosome 6. Multipoint analysis placed the 5-HT1D beta receptor gene between markers D6S286 and D6S275. A maximum two-point lod score of 10.90 was obtained to D6S26, which had been previously localized on 6q14-15. Chromosomal aberrations involving this region have been previously shown to cause retinal anomalies, developmental delay, and abnormal brain development. This region also contains the gene for North Carolina-type macular dystrophy.

Electrical activity suppresses nicotinic acetylcholine receptor gamma subunit promoter activity

Nicotinic acetylcholine receptors are pentameric, transmembrane, ligand-gated ion channels critical for neuromuscular signal transmission. Prior to innervation, the genes encoding these receptors are expressed in nuclei throughout the muscle fiber. Muscle innervation leads to a dramatic decrease in expression of these genes in extrasynaptic nuclei. This reduction in gene expression can be reversed by muscle denervation. The effects of denervation on receptor gene expression can be blocked by electrical stimulation of muscle using extracellular electrodes. The molecular mechanisms by which muscle electrical activity leads to altered patterns of nicotinic acetylcholine receptor gene expression are not well understood. Using an in vitro electrical stimulation paradigm to induce muscle activity, we have been able to mimic the effect of innervation on extrasynaptic acetylcholine receptor gene expression. We have found that a 93-bp region of 5'-flanking DNA, spanning nucleotides -150 to -57 relative to the transcription start site of the gamma subunit gene, is required for the suppression of gene expression in response to muscle activity. Sequences downstream of this region are transcriptionally active but are not responsive to muscle activity. However, these downstream sequences become responsive to muscle activity when placed under the control of the gamma subunit muscle-specific enhancer.

Detection of aldehyde dehydrogenase deficiency in Chachi Indians, Ecuador

The activity of mitochondrial aldehyde dehydrogenase (ALDH2) was tested by isoelectric focusing of hair root extracts from 50 Chachi Indians (Ecuador). Quality of extracts and the intactness of cytoplasmic and mitochondrial enzymes were ascertained by assaying of phosphoglucomutase (PGM) and malate dehydrogenase (MDH) in the same extracts. Three of the 39 successfully assayed Chachi Indian samples showed virtual absence of the ALDH2 band on the isoelectropherogram, and the control enzymes were stained normally in these subjects. These data confirm the existence of a mitochondrial ALDH deficiency among South American Indians. The molecular origin of the ALDH2 deficiency in this population is unknown.

Apparent monomorphism of ALDH2 in seven American Indian populations

Deficiency of mitochondrial aldehyde dehydrogenase (ALDH2) has been previously reported in South American Indians. We therefore assayed five individuals from each of five South American Indian populations (Quechua, Karitiana, Ticuna, Surui, Guahiba), and two North American populations (Maya and Moskoke) for the presence of the Oriental ALDH2(2) variant. These samples were also surveyed for other alleles altering ALDH2 function. Allele-specific amplification assay (ASA) did not detect the ALDH2(2) allele in any of the New World populations studied. The entire coding sequence of the ALDH2 cDNA was enzymatically amplified in partially overlapping fragments. Each fragment was digested using restriction endonucleases and subfragments 148-285 b.p. in length were analyzed by the single-stranded conformation polymorphism (SSCP) technique. No variants were detected within the coding region of the ALDH2 gene in any of the seven American Indian populations. Three potentially correct explanations for these results are suggested. First, an ALDH2 polymorphism is present but undetectable by SSCP; second, none of the studied individuals were ALDH2 negative; third, the polymorphism occurs beyond the coding region of ALDH2 gene.

Protein-tyrosine phosphatases specifically regulate muscle adult-type nicotinic acetylcholine receptor gene expression

Innervation of skeletal muscles results in expression of adult-type nicotinic acetylcholine receptors (alpha 2 beta epsilon delta) beneath the neuromuscular junction. This local expression is largely a result of selective induction of adult-type nicotinic acetylcholine receptor (nAChR) genes in endplate-associated myonuclei. The molecular mechanism by which the nerve induces gene expression in these nuclei is not known. We have shown previously that ionophore-induced calcium influx across the plasma membrane preferentially decreases expression from the adult-type specific nAChR epsilon-subunit gene (Walke, W., Staple, J., Adams, L., Gnegy, M., Chahine, K., and Goldman, D. (1994) J. Biol. Chem. 269, 19447-19456). Here we provide evidence that the genes encoding adult-type nAChRs are specifically regulated by protein-tyrosine phosphatase activity. Orthovanadate, a specific protein-tyrosine phosphatase inhibitor, caused increased expression of the epsilon-subunit gene in rat primary myotubes and was able to completely block the suppressive effects of increased calcium influx on epsilon-subunit RNA expression. Overexpression of protein-tyrosine phosphatases selectively decreased expression from the adult-type nAChR genes with no effect on the embryonic-type specific gamma-subunit gene. These results demonstrate that protein-tyrosine phosphatases regulate mammalian adult-type nAChR gene expression and suggest a mechanism by which muscle innervation selectively regulates gene expression in endplate-associated myonuclei.

Pathogenesis of pulmonary Cryptococcus neoformans infection in the rat

The pathogenesis of Cryptococcus neoformans pulmonary infection in the rat was studied after intratracheal inoculation. Lungs were examined at various times following infection for histopathology in conjunction with macrophage markers, proliferating cell nuclear antigen (PCNA), and capsular glucuronoxylomannan (GXM) antigen. Serum GXM, immunoglobulin M (IgM) and IgG titers and organ fungal burden were compared with pathological findings. C. neoformans organisms were in the lung parenchyma 2 h postinoculation, and GXM antigen was present in surrounding tissues shortly thereafter. Extrapulmonary dissemination occurred early in infection. Two phases of host cellular inflammatory response were discernible: early local macrophage recruitment at 2 to 4 days followed by granulomatous inflammation, which reached maximum intensity 14 days after infection. The granulomatous phase was preceded by lymphocyte influx with macrophage proliferation and maturation into epithelioid histiocytes; this was paralleled by a shift of yeasts from extracellular to intracellular spaces. Tissue IgG deposits, serum IgG to GXM, and localization of tissue GXM immunoreactivity to epithelioid cells were noted at 2 to 4 weeks. A 10-fold decrease in lung fungal burden occurred 25 days postinfection and was associated with resolving granulomas, fewer proliferating cells, and decreased tissue GXM. The present study demonstrates that (i) C. neoformans penetrates the lung parenchyma shortly after infection; (ii) immunocompetent rats control pulmonary cryptococcosis efficiently, with minimal extrapulmonary dissemination and low levels of serum GXM; and (iii) macrophage activation is likely to play a crucial role in limiting C. neoformans infection in the rat lung.

Polymorphic admixture typing in human ethnic populations

A panel of 257 RFLP loci was selected on the basis of high heterozygosity in Caucasian DNA surveys and equivalent spacing throughout the human genome. Probes from each locus were used in a Southern blot survey of allele frequency distribution for four human ethnic groups: Caucasian, African American, Asian (Chinese), and American Indian (Cheyenne). Nearly all RFLP loci were polymorphic in each group, albeit with a broad range of differing allele frequencies (delta). The distribution of frequency differences (delta values) was used for three purposes: (1) to provide estimates for genetic distance (differentiation) among these ethnic groups, (2) to revisit with a large data set the proportion of human genetic variation attributable to differentiation within ethnic groups, and (3) to identify loci with high delta values between recently admixed populations of use in mapping by admixture linkage disequilibrium (MALD). Although most markers display significant allele frequency differences between ethnic groups, the overall genetic distances between ethnic groups were small (.066-.098), and < 10% of the measured overall molecular genetic diversity in these human samples can be attributed to "racial" differentiation. The median delta values for pairwise comparisons between groups fell between .15 and .20, permitting identification of highly informative RFLP loci for MALD disease association studies.

Detection of mutations and polymorphisms using fluorescence-based dideoxy fingerprinting (F-ddF)

We have adapted the dideoxy finger-printing (ddF) technique for detecting DNA sequence variants to fluorescence detection (F-ddF) using an Applied Biosystems Model 373A DNA Sequencer equipped with GENESCAN 672 software and an external temperature control device. The fingerprints can be precisely aligned using an internal standard run in the same lanes. This facilitates location and characterization of mobility changes resulting from sequence variants. As compared to fluorescence detected single-strand conformation polymorphism analysis (F-SSCP), F-ddF is equally efficient for detection of sequence variants, and it offers additional advantages. These include information regarding location of the sequence variation, greater reliability for distinguishing one sequence variant from another and the capacity to generate large PCR fragments and analyze them in smaller subsegments. Read length and overall quality of data from F-ddF are sequence-dependent when Taq DNA polymerase is used, but reducing terminator concentration can extend read length. The strengths and weakness of F-ddF and F-SSCP are different. Thus F-ddF may work better in a given situation than F-SSCP and vice versa. A strategy for using F-ddF to circumvent limitations of F-SSCP is described.

Phylogenetic reconstruction of South American felids defined by protein electrophoresis

Phylogenetic associations among six closely related South American felid species were defined by changes in protein-encoding gene loci. We analyzed proteins isolated from skin fibroblasts using two-dimensional electrophoresis and allozymes extracted from blood cells. Genotypes were determined for multiple individuals of ocelot, margay, tigrina, Geoffroy's cat, kodkod, and pampas cat at 548 loci resolved by two-dimensional electrophoresis and 44 allozyme loci. Phenograms were constructed using the methods of Fitch-Margoliash and neighbor-joining on a matrix of Nei's unbiased genetic distances for all pairs of species. Results of a relative-rate test indicate changes in two-dimensional electrophoresis data are constant among all South American felids with respect to a hyena outgroup. Allelic frequencies were transformed to discrete character states for maximum parsimony analysis. Phylogenetic reconstruction indicates a major split occurred approximately 5-6 million years ago, leading to three groups within the ocelot lineage. The earliest divergence led to Leopardus tigrina, followed by a split between an ancestor of an unresolved trichotomy of three species (Oncifelis guigna, O. geoffroyi, and Lynchailuris colocolo) and a recent common ancestor of Leopardus pardalis and L. wiedii. The results suggest that modern South American felids are monophyletic and evolved rapidly after the formation of the Panama land bridge between North and South America.

Calcium-dependent regulation of rat and chick muscle nicotinic acetylcholine receptor (nAChR) gene expression

Muscle depolarization leads to decreased expression of nicotinic acetylcholine receptor (nAChR) genes in extrajunctional regions of the muscle fiber with little effect on their expression at the neuromuscular junction (NMJ). Depolarization-dependent decreases in nAChR gene expression have been linked to a cAMP-dependent signaling system in rat (Chahine, K. G., Baracchini, E., and Goldman, D. (1993) J. Biol. Chem. 2893-2898), and a calcium-dependent protein kinase C (PKC) signaling system in chick (Klarsfeld, A., Laufer, R., Fontaine, B., Devillers-Thiery, A., Bubreuil, C., and Changeux, J. P. (1989) Neuron 2, 1229-1236). We report here on experiments investigating the role of calcium and PKC in regulating rat muscle nAChR gene expression. These studies indicate that depolarization-dependent regulation of rat muscle nAChR gene expression is independent of PKC activity. However, these genes are regulated by a calcium-dependent signal transduction system. Calcium influx across the plasma membrane decreases nAChR gene expression in inactive rat myotubes. Surprisingly, this influx of extracellular calcium is most effective at reducing nAChR epsilon-subunit gene expression. We also provide evidence that a similar signal transduction system is capable of regulating nAChR gene expression in chick muscle. Based on these data we propose that calcium, in addition to mediating depolarization-dependent regulation of nAChR expression, may also participate in restricting their expression to the neuromuscular junctions of adult muscle fibers.

T helper cell dysfunction in systemic lupus erythematosus (SLE): relation to disease activity

Patients with systemic lupus erythematosus (SLE) are known to have defects in both humoral and cellular immunity. The significance of defective T cell-mediated immunity and its relationship to disease activity have not been clearly established. We studied in vitro T helper cell (Th) function in 150 SLE outpatients and correlated Th function with validated measures of disease activity. Interleukin 2 (IL-2) production by peripheral blood mononuclear cells (PBMC) was measured after stimulation with the recall antigens influenza A virus (FLU) and tetanus toxoid (TET), irradiated allogeneic peripheral blood mononuclear cells (ALLO), and phytohemagglutinin (PHA). We observed three patterns of Th response: (1) 76 of 150 (50%) of patients responded to the recall antigens FLU and/or TET, ALLO, and PHA; (2) 62 of 150 (42%) of patients did not respond to recall antigens but responded to ALLO and PHA; and (3) 12 of 150 (8%) of patients did not respond to either recall antigens or ALLO antigens. This diminished T cell function was correlated with higher disease activity as measured by four scales of clinical activity, such that individuals who exhibited more in vitro immune dysfunction presented with significant increases in their clinical activity indices. The alterations in T cell function could not be accounted for by medication doses alone. Thus, SLE patients have multiple distinct defects at the level of the Th cell which are associated with clinical measures of disease activity.

Effect of prednisone and hydroxychloroquine on coronary artery disease risk factors in systemic lupus erythematosus: a longitudinal data analysis

PURPOSE

To determine the effect of prednisone dose and hydroxychloroquine dose on the coronary artery disease risk factors serum cholesterol level, mean arterial blood pressure, and weight in patients with systemic lupus erythematosus.

PATIENTS AND METHODS

A longitudinal cohort study of 264 patients with systemic lupus erythematosus was conducted. For all patients in the cohort, serum cholesterol, mean arterial pressure, weight, prednisone dose, hydroxychloroquine dose, and other potential confounding variables were recorded at each visit. Regression analysis appropriate for longitudinal data was used to assess the effect of prednisone on serum cholesterol and mean arterial pressure. To assess the effect of prednisone on weight, patients' weights were compared 90 days before and after a 10-mg or 20-mg increase in prednisone.

RESULTS

A total of 3,027 patient visits were analyzed. In the regression model for serum cholesterol, a change in prednisone dose of 10 mg was associated with a change in cholesterol of 7.5 +/- 1.46 (SE) mg% after adjustment for the other significant variables in the model, including sex, race, hydroxychloroquine dose, and proteinuria. In the regression model for hydroxychloroquine, the 200-mg and the 400-mg dose were both associated with lower serum cholesterol (8.9 +/- 3.44 SE mg%). In the regression model for mean arterial blood pressure, a 10-mg change in prednisone dose led to a change in mean arterial blood pressure of 1.1 mm Hg after adjustment for age, weight, and antihypertensive drug use. A 10-mg increase in prednisone dose was associated with a mean weight change of 5.50 +/- 1.23 (SE) lb.

CONCLUSIONS

Changes in prednisone dose led to definable changes in risk factors for coronary artery disease, even after adjustment for other variables known to affect these risk factors. According to longitudinal regression analysis, hydroxychloroquine therapy was associated with lower serum cholesterol.

Grandmother dishonored: violence against women by male partners in American Indian communities

Extensive and scrupulously conducted research during the past decade has established the issue of violence against women by male partners as both an international human rights issue and a public health problem of national concern. This research has rarely been extended into communities of color, and, in particular, to American Indian women. This article presents conceptual and methodological factors involved in conducting research with American Indian women, a comprehensive literature review of available data, assertions regarding abuse of women by male partners in American Indian communities, and directions for future research.

Rating of medication influences (ROMI) scale in schizophrenia

Noncompliance with neuroleptic treatment is a major barrier to delivery of effective treatment for schizophrenia outpatients. This article describes the development of a standardized measure for the assessment of attitudinal and behavioral factors influencing patient compliance with neuroleptic treatment. The Rating of Medication Influences (ROMI) scale was developed as part of a longitudinal study of neuroleptic noncompliance in schizophrenia and administered to 115 discharged schizophrenia outpatients. Analyses of the following were conducted to assess the scale's psychometric properties: (1) interrater reliability, (2) internal consistency, (3) principal components, (4) correlation with other subjective measures, and (5) correlation with independent family reports. Most (95%) of the ROMI patient-report items were reliable, whereas rater-judgment items were not reliable. The rater section was dropped. A principal components analysis of the reliable patient-report items yielded three subscales related to compliance (Prevention, Influence of Others, and Medication Affinity) and five subscales related to noncompliance (Denial/Dysphoria, Logistical Problems, Rejection of Label, Family Influence, and Negative Therapeutic Alliance). There were significant correlations between these subscales, and independently obtained family-report ROMI items were significant. The Denial/Dysphoria subscale correlated strongly with two other published measures of dysphoric response to neuroleptics, whereas the other noncompliance subscales did not. The ROMI is a reliable and valid instrument that can be used to assess the patient's subjective reasons for medication compliance and non-compliance. The subscale findings suggest that the ROMI provides a more comprehensive data base for patient-reported compliance attitudes than the other available subjective measures. Indications for use of the ROMI and other subjective measures of neuroleptic response are reviewed.

Serotonin, violent behavior and alcohol

At the NIAAA intramural research program, in collaboration with investigators at the Department of Psychiatry, University of Helsinki, we have mounted an extensive research program on early onset male alcoholism. A central serotonergic deficit is common among these patients. This finding has led to behavioral, biochemical, physiological and molecular genetic studies on the serotonin system in early onset, antisocial and violent male alcoholics and in appropriate control populations. The results of the studies completed by the fall of 1993 are summarized in this communication.

Suicidality and 5-hydroxyindoleacetic acid concentration associated with a tryptophan hydroxylase polymorphism

BACKGROUND

To examine whether the tryptophan hydroxylase (TPH) gene, which codes for the rate-limiting enzyme in the biosynthesis of serotonin, may be a factor influencing serotonin turnover and behaviors controlled by serotonin.

METHODS

Using a polymerase chain reaction-based method, TPH genotype was determined in DNA samples from 56 impulsive and 14 nonimpulsive, alcoholic, violent offenders and 20 healthy volunteers.

RESULTS

In the behaviorally extreme impulsive group, we observed a significant association between TPH genotype and cerebrospinal fluid 5-hydroxyindoleacetic acid (5-HIAA) concentration. No association of TPH genotype with impulsive behavior was detected. The polymorphism was also associated with a history of suicide attempts in all violent offenders, independent of impulsivity status and cerebrospinal fluid 5-HIAA concentration.

CONCLUSION

In some individuals, a genetic variant of the TPH gene may influence 5-HIAA concentration in the cerebrospinal fluid and predisposition to suicidal behavior.