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Talkowski ME, McClain L, Allen T, Bradford LD, Calkins M, Edwards N, Georgieva L, Go R, Gur R, Gur R, Kirov G, Chowdari K, Kwentus J, Lyons P, Mansour H, McEvoy J, O’ Donovan MC, O’Jile J, Owen MJ, Santos A, Savage R, Toncheva D, Vockley G, Wood J, Devlin B, Nimgaonkar VL. Convergent patterns of association between phenylalanine hydroxylase variants and schizophrenia in four independent samples. Am J Med Genet B Neuropsychiatr Genet 2009; 150B:560-9. [PMID: 18937293 PMCID: PMC2738981 DOI: 10.1002/ajmg.b.30862] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Recessive mutations in the phenylalanine hydroxylase (PAH) gene predispose to phenylketonuria (PKU) in conjunction with dietary exposure to phenylalanine. Previous studies have suggested PAH variations could confer risk for schizophrenia, but comprehensive follow-up has not been reported. We analyzed 15 common PAH "tag" SNPs and three exonic variations that are rare in Caucasians but common in African-Americans among four independent samples (total n = 5,414). The samples included two US Caucasian cohorts (260 trios, 230 independent cases, 474 controls), Bulgarian families (659 trios), and an African-American sample (464 families, 401 controls). Analyses of both US Caucasian samples revealed associations with five SNPs; most notably the common allele (G) of rs1522305 from case-control analyses (z = 2.99, P = 0.006). This SNP was independently replicated in the Bulgarian cohort (z = 2.39, P = 0.015). A non-significant trend was also observed among African-American families (z = 1.39, P = 0.165), and combined analyses of all four samples were significant (rs1522305: chi(2) = 23.28, 8 d.f., P = 0.003). Results for rs1522305 met our a priori criteria for statistical significance, namely an association that was robust to multiple testing correction in one sample, a replicated risk allele in multiple samples, and combined analyses that were nominally significant. Case-control results in African-Americans detected an association with L321L (P = 0.047, OR = 1.46). Our analyses suggest several associations at PAH, with consistent evidence for rs1522305. Further analyses, including additional variations and environmental influences such as phenylalanine exposure are warranted.
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Affiliation(s)
- Michael E. Talkowski
- Department of Psychiatry, University of Pittsburgh, Sofia, Bulgaria
,Department of Human Genetics, University of Pittsburgh, Sofia, Bulgaria
| | - Lora McClain
- Department of Psychiatry, University of Pittsburgh, Sofia, Bulgaria
| | - Trina Allen
- Department of John Umstead Hospital, Duke University Medical Center, Sofia, Bulgaria
| | | | - Monica Calkins
- Department of Psychiatry, University of Pennsylvania, Sofia, Bulgaria
| | - Neil Edwards
- Department of Psychiatry, University of Tennessee, Sofia, Bulgaria
| | - Lyudmila Georgieva
- Department of Psychological Medicine, Cardiff University School of Medicine, Sofia, Bulgaria
| | - Rodney Go
- Department of Psychiatry, Behavioral Neurobiology, and Epidemiology, University of Alabama Birmingham, Sofia, Bulgaria
| | - Ruben Gur
- Department of Psychiatry, University of Pennsylvania, Sofia, Bulgaria
| | - Raquel Gur
- Department of Psychiatry, University of Pennsylvania, Sofia, Bulgaria
| | - George Kirov
- Department of Psychological Medicine, Cardiff University School of Medicine, Sofia, Bulgaria
| | | | - Joseph Kwentus
- Department of Psychiatry and Human Behavior, University of Mississippi, Sofia, Bulgaria
| | - Paul Lyons
- Department of Neurology, University of Virginia, Sofia, Bulgaria
| | - Hader Mansour
- Department of Psychiatry, University of Pittsburgh, Sofia, Bulgaria
| | - Joseph McEvoy
- Department of John Umstead Hospital, Duke University Medical Center, Sofia, Bulgaria
| | - Michael C. O’ Donovan
- Department of Psychological Medicine, Cardiff University School of Medicine, Sofia, Bulgaria
| | - Judith O’Jile
- Department of Psychiatry and Human Behavior, University of Mississippi, Sofia, Bulgaria
| | - Michael J. Owen
- Department of Psychological Medicine, Cardiff University School of Medicine, Sofia, Bulgaria
| | - Alberto Santos
- Department of Psychiatry and Behavioral Sciences, Medical University of South Carolina, Sofia, Bulgaria
| | - Robert Savage
- Department of Psychiatry, Behavioral Neurobiology, and Epidemiology, University of Alabama Birmingham, Sofia, Bulgaria
| | - Draga Toncheva
- Department of Medical Genetics, Medical University, Sofia, Bulgaria
| | - Gerard Vockley
- Department of Pediatrics, University of Pittsburgh, Sofia, Bulgaria
| | - Joel Wood
- Department of Psychiatry, University of Pittsburgh, Sofia, Bulgaria
| | - Bernie Devlin
- Department of Psychiatry, University of Pittsburgh, Sofia, Bulgaria
,Department of Human Genetics, University of Pittsburgh, Sofia, Bulgaria
| | - Vishwajit L. Nimgaonkar
- Department of Psychiatry, University of Pittsburgh, Sofia, Bulgaria
,Department of Human Genetics, University of Pittsburgh, Sofia, Bulgaria
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Richardson MA, Read LL, Clelland JD, Chao HM, Reilly MA, Romstad A, Suckow RF. Phenylalanine hydroxylase gene in psychiatric patients: screening and functional assay of mutations. Biol Psychiatry 2003; 53:543-53. [PMID: 12644360 DOI: 10.1016/s0006-3223(02)01528-7] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
BACKGROUND Reports relating phenylalanine kinetics and metabolism to psychiatric disorders led us to undertake the comprehensive screening of the phenylalanine hydroxylase (PAH) coding region and functional testing of discovered mutations in a sample of psychiatric patients and healthy control subjects. METHODS Genomic DNA from psychiatric patients and control subjects was assayed for sequence variants in all PAH coding regions and splice junctions. In vivo functional analysis of mutations was conducted by assessing the kinetics and conversion to tyrosine of a standardized phenylalanine dose and by measuring fasting pterin levels. RESULTS A known missense mutation was observed in a schizoaffective subject, and a novel missense mutation was discovered in four subjects with schizophrenia and one normal subject. The schizoaffective patient heterozygous for the known A403V mutation showed the lowest rate of phenylalanine kinetics and lowest conversion to tyrosine in the patient sample. The four schizophrenic patients heterozygous for the novel K274E mutation showed significantly decreased phenylalanine kinetics, reduced conversion to tyrosine, and increased synthesis of the PAH cofactor tetrahydrobiopterin compared with schizophrenic subjects without the mutation. CONCLUSIONS The study findings suggest that larger scale studies are warranted to test the relationship of the PAH genotype with a psychiatric phenotype.
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Affiliation(s)
- Mary Ann Richardson
- Nathan S. Kline Institute for Psychiatric Research, New York State Office of Mental Health, Orangeburg 10962, USA
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Schultz SK, Ellingrod V, Fleming FW, Andreasen NC. The association between risk factors for tardive dyskinesia and phenylalanine-induced abnormal movements in schizophrenia. Hum Psychopharmacol 2001; 16:273-277. [PMID: 12404580 DOI: 10.1002/hup.245] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
We examined whether an oral challenge dose of the amino acid phenylalanine (a dopamine precursor) exacerbates the abnormal movements of tardive dyskinesia (TD). We also examined age, gender, treatment duration, and baseline movement severity in relation to phenylalanine-induced changes in movements. Lastly, we assessed the influence of fasting amino acid levels on phenylalanine-induced movements. In a placebo-controlled fashion, the abnormal involuntary movement scale (AIMS) was obtained on 25 patients before and after a phenylalanine challenge drink. A general linear model determined the relative effects of age, gender, treatment duration, and fasting amino acid levels on the magnitude of induced movements. Age and treatment duration did not affect phenylalanine-induced movements. Lower fasting levels of phenylalanine were associated with greater movements after controlling for age, F = 11.89, p < 0.003. The severity of abnormal movements at baseline also predicted response to phenylalanine, F = 8.62, p = 0.0079. Brain amino acid and neurotransmitter pools are influenced by changes in dietary protein, which may have implications in the development and prevention of movement disorders. This study suggests that fasting amino acid levels may predict differences in vulnerability to movements during an influx of neurotransmitter precursors, perhaps due to long-term compensatory changes in receptor sensitivity. Copyright 2001 John Wiley & Sons, Ltd.
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Affiliation(s)
- S. K. Schultz
- Mental Health Clinical Research Center, University of Iowa, Iowa City, IA, USA
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Abstract
The hypothesis that phenylethylamine (PEA) is an endogenous psychotogen in schizophrenics, particularly those with the paranoid subtype, has been previously studied by measuring PEA levels in urine and cerebrospinal fluid (CSF) of schizophrenic patients. However, plasma PEA may more accurately reflect simultaneous alterations of PEA in many organ systems, as might occur in a genetic disorder of PEA metabolism. No study to date has examined phenylalanine (Phe), which is thought to be a precursor of PEA, in the same patients who had PEA measured. In this study, we measure both plasma PEA and Phe in 17 drug-free schizophrenic patients and 17 matched controls. Plasma PEA in normal controls was found to be lower by three orders of magnitude compared to normal controls from previous studies--a finding that has not previously been reported. PEA was significantly lower in those schizophrenic patients who had a Research Diagnostic Criteria diagnosis of paranoid schizophrenia. PEA did not differ between patients and controls, and the correlation between plasma Phe and PEA was not significant.
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Moises HW, Waldmeier P, Beckmann H. Urinary phenylethylamine correlates positively with hypomania, and negatively with depression, paranoia, and social introversion on the MMPI. EUROPEAN ARCHIVES OF PSYCHIATRY AND NEUROLOGICAL SCIENCES 1986; 236:83-7. [PMID: 3792411 DOI: 10.1007/bf00454016] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
It has been suggested that phenylethylamine (PEA) may play a role in the modulation of affective behavior. The aim of the present study was to test this hypothesis. Urinary PEA excretion was determined in 32 drug-free healthy volunteers, and the MMPI was used for personality assessment. In support of this hypothesis, a significant positive correlation between PEA and hypomania (r = 0.50; P less than 0.05) and a significant negative correlation between PEA and depression (r = -0.58; P less than 0.01) was observed in the female subgroup. Furthermore, PEA correlated significantly negatively with hypochondriasis (r = -0.65; P less than 0.01), paranoia (r = 0.49; P less than 0.05), and social introversion (r = -0.60; P less than 0.05). These results are the first evidence in normal individuals either that PEA itself might play a role in the modulation of affective behavior, or alternatively that PEA could be related to mechanisms responsible for the modulation of affective behavior.
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