PER2

Chr 2

period circadian regulator 2

Also known as: FASPS, FASPS1

NCBI Gene: 8864ENSG00000132326UniProt: O15055

This gene is a member of the Period family of genes and is expressed in a circadian pattern in the suprachiasmatic nucleus, the primary circadian pacemaker in the mammalian brain. Genes in this family encode components of the circadian rhythms of locomotor activity, metabolism, and behavior. This gene is upregulated by CLOCK/ARNTL heterodimers but then represses this upregulation in a feedback loop using PER/CRY heterodimers to interact with CLOCK/ARNTL. Polymorphisms in this gene may increase the risk of getting certain cancers and have been linked to sleep disorders. [provided by RefSeq, Jan 2014]

ResearchGenerating clinical summary…

Primary Disease Associations & Inheritance

UniProtAdvanced sleep phase syndrome, familial, 1

Clinical highlights

Interpreting a novel variant
This gene is strongly intolerant of loss-of-function variation in the population, so LoF variants warrant close attention. No curated mechanism annotation is available — see the mechanism card for the computational prediction and its caveats.Based on population constraint only.
9
Active trials
292
Pubs (1 yr)
—
P/LP submissions
—
P/LP missense
0.35
LOEUF· LoF intol.
LOF
Mechanism· predicted
Some data sources returned errors (1)

omim: Error: OMIM fetch failed: 429

Population Genetics & Constraint

gnomAD v4 — loss-of-function & missense intolerance

gnomAD
LoF intolerant — likely haploinsufficient
LoF Constraint?
0.35LOEUF
pLI 0.715
Z-score 5.31
OE 0.21 (0.13–0.35)
Highly constrained

Highly LoF-intolerant (top ~10% of genes)

Missense Constraint?
0.43Z-score
OE missense 0.96 (0.90–1.02)
706 obs / 738.6 exp
Tolerant

Mild missense constraint

Observed / Expected Ratios?
LoF OE?0.21 (0.13–0.35)
0≤0.351.4
Missense OE?0.96 (0.90–1.02)
0≤0.61.4
Synonymous OE?1.04
0≤1.21.6
LoF obs/exp: 11 / 52.5Missense obs/exp: 706 / 738.6Syn Z: -0.50

ClinVar Variant Classifications

0 submitted variants in ClinVar

ClinVar

Protein Context — Lollipop Plot

PER2 · protein map & ClinVar variants

Showing all ClinVar variants across the protein. Search a specific variant to highlight its position.

Clinical Trials

Active and recruiting trials from ClinicalTrials.gov

ClinicalTrials.gov
Fibromyalgia (FM)tDCSDuloxetine

Home-based Transcranial Direct Current Stimulation (tDCS) Compared to Duloxetine: Non-inferiority Clinical Trial (FIBROSTIM)

RECRUITING
NCT07203339Phase NAHospital de Clinicas de Porto AlegreStarted 2025-09-30
Transcranial direct current stimulation (tDCS) plus placebo.Duloxetine (60 mg) once dailyHome-based transcranial direct current stimulation
Multiple Sclerosis

Understanding the Impact of Meal Timing on Neurological Health in Adults With Multiple Sclerosis

NOT YET RECRUITING
NCT07475377Phase NAUniversity of Alabama at BirminghamStarted 2026-08-01
Time Restricted EatingUnrestricted eating
Polycystic Ovary SyndromeDiminished Ovarian ReserveOvulation Disorder

Clinical Trial of Anovulatory Infertility

ENROLLING BY INVITATION
NCT06601452Phase EARLY_PHASE1Affiliated Hospital of Nanjing University of Chinese MedicineStarted 2024-09-30
a compound prescription of Chinese medicine
Critical Illness

The Effect of Continuous Versus Intermittent Enteral Nutrition on Metabolic Outcomes in Critically Ill Patients

RECRUITING
NCT07173504Phase NAGelderse Vallei HospitalStarted 2025-09-30
Intermittent enteral nutrition
GingivitisCircadian Rhythm DisruptionPeriodontal Inflammation

Circadian Clock Proteins in Gingival Crevicular Fluid of Individuals With and Without Circadian Rhythm Disruption

NOT YET RECRUITING
NCT07592052Inonu UniversityStarted 2026-08-01
Standard Periodontal Treatment
Obesity (Disorder)Morbid ObesityBariatric Sleeve Gastrectomy

Chrono-ALIGN: A Chronotype-Based Chrono-Nutrition Intervention in Post-Bariatric Patients

NOT YET RECRUITING
NCT07324044Phase NAKing Saud UniversityStarted 2026-01-01
Standard Post-Bariatric Care (Control)Early Time-Restricted Eating (eTRE)Chronotype-Based Chrono-Nutrition (CB-CN)
Bipolar Disorder II

Efficacy and Mechanism of IPSRT for Bipolar II Disorder

NOT YET RECRUITING
NCT07654348Phase PHASE2First Affiliated Hospital of Zhejiang UniversityStarted 2026-07-01
Quetiapine (drug)Psychopharmacological treatment
Healthy Children

To Investigate the Effects of Bifidobacterium Animalis Subsp. Lactis XLTG11 on Growth and Development, Incidence of Allergy and Immune Function in Infants

RECRUITING
NCT07490587Phase PHASE2Min-Tze LIONGStarted 2024-01-01
ProbioticPlacebo
Cystic Fibrosis

Circadian Rhythm Disorders in Children With Cystic Fibrosis Under CFTR (Cystic Fibrosis Transmembrane Conductance Regulator) Modulators

RECRUITING
NCT06370962Hospices Civils de LyonStarted 2024-04-29

External Resources

Links to major genomics databases and tools

Franklin by Genoox
AI-powered variant curation and clinical analysis
DECIPHER
Genomic variants and phenotypes in rare disease patients