Vitamin D Binding Protein (Gc) Allele Variation Effects Response to Vitamin D Treatment (Gc)

We have just completed a randomized, clinical trial of 100,000 IU Vitamin D3 given as a single dose at the beginning of winter. We found a wide range of responses to the dose. This study proposes that genetic differences account for some of the variation in response of 25(OH)D levels after treatment with oral Vitamin D.

Study Overview

• Status: Completed
• Conditions: Vitamin D Status

Detailed Description

We suspect that the wide range of response is effected by other factors such as variation in Vitamin D binding protein (the major transporter of Vitamin D metabolites).

Gc, also known as Vitamin D binding protein (DBP), group specific component, or Gc globulin, is a 52-58 kDa multifunctional plasma protein, synthesized in the liver. The gene encoding for Gc is located on chromosome 4, and three common co-dominant alleles give rise to three phenotypes (Gc1s, Gc1f, and Gc2). Gc binds actin, recruits neutrophil leukocytes and converts into a macrophage- and osteoclast- activating factor. It also is the major transporter of Vitamin D and its' metabolites. Lauridsen et al. showed that Gc phenotype correlates with 25(OH)D levels in a group of postmenopausal women.

This study proposes that Gc phenotype accounts for some of the variation in response of 25(OH)D levels after treatment with oral Vitamin D.

• Study Type: Observational
• Enrollment (Actual): 29

Contacts and Locations

Study Locations

• United States
  • Nebraska
    • Omaha, Nebraska, United States, 68131
      • Creighton University

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 19 years to 90 years (Adult, Older Adult)
• Accepts Healthy Volunteers: Yes
• Genders Eligible for Study: All

• Sampling Method: Non-Probability Sample

Study Population

This study will include thirty males and females who took part in a previous study of a single oral dose of vitamin D.

Description

Inclusion Criteria:

• Must be willing to participate with an additional blood draw.
• Must have been in the previous study.

Exclusion Criteria:

• Will not be eligible if not a part of the previous study

Study Plan

How is the study designed?

Number of groups / cohorts

1

Cohorts and Interventions

Group / Cohort
1; All of the subjects will have measurements of Gc concentration and phenotype

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Time Frame
Gc concentration and phenotype	at 1st visit

Collaborators and Investigators

• Sponsor: Creighton University
• Investigators: Principal Investigator: Laura Armas, MD, Creighton University

Study record dates

Study Major Dates

• Study Start: October 1, 2007
• Primary Completion (Actual): January 1, 2008
• Study Completion (Actual): January 1, 2008

Study Registration Dates

• First Submitted: March 30, 2008
• First Submitted That Met QC Criteria: April 1, 2008
• First Posted (Estimate): April 2, 2008

Study Record Updates

• Last Update Posted (Estimate): April 2, 2008
• Last Update Submitted That Met QC Criteria: April 1, 2008
• Last Verified: March 1, 2008

More Information

Terms related to this study

• Keywords: Viatmin D, 25-hydroxyvitamin D, Vitamin D binding protein
• Other Study ID Numbers: Creighton4