Association of the length polymorphism in the human Per3 gene with the delayed sleep-phase syndrome: does latitude have an influence upon it?
OBJECTIVE
The objective of this study is to analyze the influence of a previously reported hPer3 gene-length polymorphism in the delayed sleep-phase syndrome and in morningness-eveningness tendencies at low latitudes in the southern hemisphere.


METHODS
We have genotyped a length polymorphism in the hPer3 gene characterized by a short repeat allele (4-repeat) and a long repeat allele (5-repeat).


METHODS
Seventeen patients with delayed sleep-phase syndrome; 156 volunteers chosen according to Horne-Ostberg questionnaire to have morning, intermediate, or evening preference; and 110 volunteers with no Horne-Ostberg score as a sample of the general population.


RESULTS
We have found a higher frequency of 5-repeat allele in the delayed sleep-phase syndrome group and an association of this polymorphism with diurnal preference.


CONCLUSIONS
Our results suggest that latitude has a role in the influence of hPer3 gene polymorphism on delayed sleep-phase syndrome and confirm previous data showing its association with morningness-eveningness tendencies.
Pereira
Danyella S
DS
Department of Psychobiology/Sleep Institute, Universidade Federal de São Paulo, Brazil.
Tufik
Sergio
S
Louzada
Fernando M
FM
Benedito-Silva
Ana A
AA
Lopez
Alberto R
AR
Lemos
Nelson A
NA
Korczak
Anna L
AL
D'Almeida
Vania
V
Pedrazzoli
Mario
M
D000328:Adult; D001938:Brazil; D002940:Circadian Rhythm / Q000235:genetics; D005260:Female; D005787:Gene Frequency / Q000235:genetics; D005838:Genotype; D005843:Geography; D006801:Humans; D008297:Male; D009687:Nuclear Proteins / Q000235:genetics*; D056950:Period Circadian Proteins; D011110:Polymorphism, Genetic / Q000235:genetics*; D012720:Severity of Illness Index; D020178:Sleep Disorders, Circadian Rhythm / Q000175:diagnosis / Q000235:genetics*; D011795:Surveys and Questionnaires; D014157:Transcription Factors
D009687:Nuclear Proteins; C512644:PER3 protein, human; D056950:Period Circadian Proteins; D014157:Transcription Factors