A single nucleotide polymorphism in glycogen synthase kinase 3-beta promoter gene influences onset of illness in patients affected by bipolar disorder.
Genetic studies in medicine exploited age of onset as a criterion to delineate subgroups of illness. Bipolar patients stratified with this criterion were shown to share clinical characteristics and patterns of inheritance of illness. The molecular mechanisms driving the biological clock in the suprachiasmatic nucleus of the hypothalamus may play a role in mood disorders. A single nucleotide polymorphism (SNP) (-50 T/C) falling into the effective promoter region (nt -171 to +29) of the gene coding for glycogen synthase kinase 3-beta (GSK3-beta) has been identified. GSK3-beta codes for an enzyme which is a target for the action of lithium and which is also known to regulate circadian rhythms in Drosophila. We studied the effect of this polymorphism on the age at onset of bipolar disorder type I. A homogeneous sample of 185 Italian patients affected by bipolar disorder was genotyped. Age at onset was retrospectively ascertained with best estimation procedures. No association was detected between GSK3-beta -50 T/C SNP and the presence of bipolar illness. Homozygotes for the wild variant (T/T) showed an earlier age at onset than carriers of the mutant allele (F=5.53, d.f.=2,182, P=0.0047). Results warrant interest for the variants of genes pertaining to the molecular clock as possible endophenotypes of bipolar disorder, but caution ought to be taken in interpreting these preliminary results and future replication studies must be awaited.
Benedetti
Francesco
F
Istituto Scientifico Universitario Ospedale San Raffaele, Department of Neuropsychiatric Sciences, Milan, Italy. benedetti.francesco@hsr.it
Bernasconi
Alessandro
A
Lorenzi
Cristina
C
Pontiggia
Adriana
A
Serretti
Alessandro
A
Colombo
Cristina
C
Smeraldi
Enrico
E
D000293:Adolescent; D000328:Adult; D017668:Age of Onset; D000368:Aged; D018692:Antimanic Agents / Q000494:pharmacology; D001714:Bipolar Disorder / Q000201:enzymology* / Q000453:epidemiology / Q000235:genetics*; D002648:Child; D002940:Circadian Rhythm / Q000235:genetics*; D004252:DNA Mutational Analysis; D029721:Drosophila Proteins / Q000235:genetics; D005260:Female; D005787:Gene Frequency; D005820:Genetic Testing; D005838:Genotype; D038362:Glycogen Synthase Kinase 3 / Q000172:deficiency* / Q000235:genetics; D000071679:Glycogen Synthase Kinase 3 beta; D006720:Homozygote; D006801:Humans; D007558:Italy / Q000453:epidemiology; D008094:Lithium / Q000494:pharmacology; D008297:Male; D008875:Middle Aged; D020641:Polymorphism, Single Nucleotide / Q000235:genetics*; D011401:Promoter Regions, Genetic / Q000235:genetics; D013493:Suprachiasmatic Nucleus / Q000201:enzymology* / Q000503:physiopathology
D018692:Antimanic Agents; D029721:Drosophila Proteins; D008094:Lithium; D000071679:Glycogen Synthase Kinase 3 beta; C080335:Sgg protein, Drosophila; D038362:Glycogen Synthase Kinase 3