Polymorphisms in the Vitamin D System and Health

This study is ongoing, but not recruiting participants.
Sponsor:
Information provided by (Responsible Party):
Rolf Jorde, University of Tromso
ClinicalTrials.gov Identifier:
NCT01395303
First received: July 14, 2011
Last updated: October 29, 2012
Last verified: October 2012
  Purpose

Polymorphisms in the vitamin D system appear to affect the serum 25(OH)D levels. If so one would expect these polymorphisms to be associated with vitamin D related conditions and diseases, which will be tested in the present study including DNA analyses in 9700 subjects


Condition
Infarction
Stroke
Diabetes
Fracture
Aortic Stenosis
Cancer
Death

Study Type: Observational
Study Design: Time Perspective: Retrospective
Official Title: Polymorphisms in the Vitamin D System and Health

Resource links provided by NLM:


Further study details as provided by University of Tromso:

Biospecimen Retention:   Samples With DNA

DNA from blood clots


Estimated Enrollment: 9700
Study Start Date: April 2011
Estimated Study Completion Date: July 2014
Estimated Primary Completion Date: October 2013 (Final data collection date for primary outcome measure)
Groups/Cohorts
myocardial infarction
subjects with myocardial infarction in the Tromsø study end point registry
type 2 diabetes
subjects with type 2 diabetes in the Tromsø study end point registry
stroke
subjects with stroke in the Tromsø study end point registry
fracture
subjects with fracture in the Tromsø study end point registry
cancer
subjects with cancer in the Tromsø study end point registry
death
subjects registered as dead in the Tromsø study end point registry
aortic stenosis
subjects with aortic stenosis in the Tromsø study end point registry
control group
randomly selected controls from the Tromsø study

Detailed Description:

Vitamin D, which is essential in calcium metabolism, is produced in the skin after sun exposure or obtained from food, mainly fatty fish or vitamin D supplements. For activation vitamin D must be hydroxylated in the liver to 25(OH)D and thereafter in the kidney to 1,25(OH)2D. In the circulation 25(OH)D and 1,25(OH)2D are bound to a carrier protein (DBP), and for 1,25(OH)2D to exert its effect it has to bind to the vitamin D receptor (VDR).

The serum level of 25(OH)D, which is the metabolite used to evaluate a person's vitamin D status, is in part genetically determined and several polymorphisms with effects on serum 25(OH)D have been identified. These polymorphisms, where the minor allele frequencies vary between 16 and 40 %, appear as important for the serum 25(OH)D level as the effect of season, physical activity or vitamin D supplementation.

Vitamin D is not only vital for the skeleton, but appears to be related to a number of health outcomes, including mortality as previously demonstrated in the Tromsø study. However, as the serum level of 25(OH)D is strongly influenced by life-style factors that are also related to health outcomes, it is difficult to decide whether the relation between vitamin D and health is causal or not.

On the other hand, the polymorphisms are not influenced by life-style, and the effect of the polymorphisms will be life-long. Accordingly, they may be a better marker of vitamin D status than a single serum 25(OH)D measurement. Furthermore, there are a number of polymorphisms regarding the vitamin D receptor (VDR) that may be associated with health.

In the present study we will therefore relate the polymorphisms affecting the serum 25(OH)D level and the function of the VDR, with anthropometric and biochemical measures, mortality, diseases and risk factors for disease. DNA will be obtained from the 4th Tromsø study.

If we find the expected associations between the polymorphisms and diseases, this will further strengthen the role of vitamin D in human health, and may be important for recommendations regarding vitamin D supplementation. Considering the high prevalence of vitamin D deficiency world wide, this may potentially have huge consequences for public health.

The main purpose of the present study is the vitamin D system, but in the Tromsø study we have previously also found a number of associations between thyroid and androgen function and health. Obtaining DNA for analysis will be the major cost in the project, whereas analyses of individual polymorphisms are relatively cheap. We will therefore also include polymorphisms regarding thyroid and androgen function.

  Eligibility

Ages Eligible for Study:   30 Years to 90 Years
Genders Eligible for Study:   Both
Accepts Healthy Volunteers:   Yes
Sampling Method:   Probability Sample
Study Population

Subjects from the fourth Tromsø study performed in 1994-1995 who had blood samples taken for later DNA analyses

Criteria

Inclusion Criteria:

  • participated in the fourth Tromsø study, later registered in our end point registry or selected as a control subject

Exclusion Criteria:

  • lacking DNA sample
  Contacts and Locations
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Please refer to this study by its ClinicalTrials.gov identifier: NCT01395303

Locations
Norway
University of Tromsø
Tromsø, Norway, 9037
Sponsors and Collaborators
University of Tromso
Investigators
Principal Investigator: Rolf Jorde, Professor University of Tromso
  More Information

No publications provided by University of Tromso

Additional publications automatically indexed to this study by ClinicalTrials.gov Identifier (NCT Number):
Responsible Party: Rolf Jorde, Professor, University of Tromso
ClinicalTrials.gov Identifier: NCT01395303     History of Changes
Other Study ID Numbers: UIT-ENDO-2011-2
Study First Received: July 14, 2011
Last Updated: October 29, 2012
Health Authority: Norway:National Committee for Medical and Health Research Ethics

Keywords provided by University of Tromso:
infarction
stroke
diabetes
fracture
aortic stenosis
cancer
death
vitamin D
androgens
thyroid hormones

Additional relevant MeSH terms:
Aortic Valve Stenosis
Constriction, Pathologic
Death
Diabetes Mellitus
Fractures, Bone
Infarction
Stroke
Heart Valve Diseases
Heart Diseases
Cardiovascular Diseases
Ventricular Outflow Obstruction
Pathological Conditions, Anatomical
Pathologic Processes
Glucose Metabolism Disorders
Metabolic Diseases
Endocrine System Diseases
Wounds and Injuries
Ischemia
Necrosis
Cerebrovascular Disorders
Brain Diseases
Central Nervous System Diseases
Nervous System Diseases
Vascular Diseases
Vitamin D
Ergocalciferols
Vitamins
Bone Density Conservation Agents
Physiological Effects of Drugs
Pharmacologic Actions

ClinicalTrials.gov processed this record on July 20, 2014