Sensory gating and alpha-7 nicotinic receptor gene allelic variants in schizoaffective disorder, bipolar type.
OBJECTIVE
Single nucleotide allelic variants in the promoter region of the chromosome 15 alpha-7 acetylcholine nicotinic receptor gene (CHRNA7) are associated with both schizophrenia and the P50 auditory evoked potential sensory gating deficit. The purpose of this study was to determine if CHRNA7 promoter allelic variants are also associated with abnormal P50 ratios in persons with schizoaffective disorder, bipolar type.


METHODS
P50 auditory evoked potentials were recorded in a paired stimulus paradigm in 17 subjects with schizoaffective disorder, bipolar type. The P50 test to conditioning ratio was used as the measure of sensory gating. Mutation screening of the CHRNA7 promoter region was performed on the subjects' DNA samples. Comparisons to previously obtained data from persons with schizophrenia and controls were made.


RESULTS
Subjects with schizophrenia, regardless of allele status, had an abnormal mean P50 ratio. Subjects with schizoaffective disorder, bipolar type and a variant allele had an abnormal mean P50 ratio, whereas those schizoaffective subjects with the common alleles had a normal mean P50 ratio. Normal control subjects had a normal mean ratio, but controls with variant alleles had higher P50 ratios.


CONCLUSIONS
In persons with bipolar type schizoaffective disorder, CHRNA7 promoter region allelic variants are linked to the capacity to inhibit the P50 auditory evoked potential and thus are associated with a type of illness genetically and biologically more similar to schizophrenia.
Martin
Laura F
LF
Department of Psychiatry, Denver Veterans Affairs Medical Center, Denver, Colorado 80262, USA. laura.martin@uchsc.edu
Leonard
Sherry
S
Hall
Mei-Hua
MH
Tregellas
Jason R
JR
Freedman
Robert
R
Olincy
Ann
A
D000328:Adult; D001714:Bipolar Disorder / Q000235:genetics* / Q000503:physiopathology / Q000523:psychology; D039721:Diagnostic and Statistical Manual of Mental Disorders; D005072:Evoked Potentials, Auditory / Q000235:genetics*; D005260:Female; D005838:Genotype; D006801:Humans; D007406:Interview, Psychological; D008126:Lod Score; D008297:Male; D008875:Middle Aged; D011110:Polymorphism, Genetic; D011401:Promoter Regions, Genetic; D011618:Psychotic Disorders / Q000235:genetics* / Q000503:physiopathology; D011978:Receptors, Nicotinic / Q000235:genetics*; D012559:Schizophrenia / Q000235:genetics* / Q000503:physiopathology; D064569:alpha7 Nicotinic Acetylcholine Receptor
C579167:Chrna7 protein, human; D011978:Receptors, Nicotinic; D064569:alpha7 Nicotinic Acetylcholine Receptor