Assays and methods of treatment relating to vitamin D insufficiency

Patent metadata

Field	Value
Publication number	US-9606131-B2
Application number	US-201514709315-A
Country	US
Kind code	B2
Filing date	May 11, 2015
Priority date	Jan 7, 2011
Publication date	Mar 28, 2017
Grant date	Mar 28, 2017

Abstract

Described herein are assays directed to determining the level of bioavailable or free vitamin D in a blood sample in a subject. The values determined for bioavailable or free vitamin D indicate whether the subject suffers from insufficient levels of vitamin D. Also described herein are methods of treatment for vitamin D insufficiency.

First claim

What is claimed is:

1. A method comprising:
determining a level of bioavailable Vitamin D in a subject by directly detecting levels of free Vitamin D and Vitamin D bound to albumin in a sample comprising serum or plasma from the subject using a differential affinity precipitation assay; and
detecting the presence of a vitamin D binding protein variant genotype in the subject.

2. The method of claim 1 , wherein the differential affinity precipitation assay comprises:
contacting a sample comprising serum or plasma from the subject with purified Vitamin D Binding Polypeptide (VDBP), wherein the purified VDBP is immobilized on a substrate, for a time sufficient for free and albumin-bound Vitamin D in the sample to bind to the purified VDBP, thereby forming test sample Vitamin D-VDBP complexes;
optionally removing any Vitamin D not bound to the purified VDBP from the test sample;
contacting the Vitamin D-VDBP complexes with a known amount of free labeled Vitamin D, for a time sufficient for the labeled Vitamin D to equilibrate with the Vitamin D-VDBP complexes in the test sample;
determining the amount of labeled Vitamin D bound to the purified VDBP in the test sample, and
calculating the amount of bioavailable Vitamin D in the sample from the subject based on the amount of labeled Vitamin D bound to the purified VDBP in the test sample.

3. The method of claim 2 , wherein the substrate is a bead or a solid surface.

4. The method of claim 2 , wherein the free labeled Vitamin D is labeled with a radiologically detectable tag; a fluorescent tag; a luminescent tag; or a colorimetric tag.

5. The method of claim 1 , wherein detecting the presence of the vitamin D binding protein variant genotype comprises detecting the presence of a Gc1F, Gc1S, or Gc2 protein variant.

6. The method of claim 5 , wherein detecting the presence of the vitamin D binding protein variant genotype comprises using chromatography, mass spectrometry, antibodies directed against the specific variants, or genotyping the subject's DNA.

7. The method of claim 6 , wherein genotyping the subject's DNA comprises determining the identity of the nucleotides at rs4588 and rs7041.

8. The method of claim 7 , wherein the presence of a G genotype at rs7041 and a C genotype at rs4588 indicates the presence of the Gc1S variant of the Vitamin D binding protein; the presence of a T genotype at rs7041 and a C genotype at rs4588 indicates the presence of the Gc1F variant of the Vitamin D binding protein; and the presence of a T genotype at rs7041 and an A genotype at rs4588 indicates the presence of the Gc2 variant of the Vitamin D binding protein.

Assignees

• Massachusetts Gen Hospital
• Beth Isreal Deaconess Medical Center Inc
• Beth Israel Deaconess Medical Ct Inc

Inventors

• Thadhani Ravi
• Karumanchi S Ananth
• Berg Anders Hayden
• Bhan Ishir

Classifications

• C12Q1/6883

  for diseases caused by alterations of genetic material · CPC title

• C12Q2600/156

  Polymorphic or mutational markers · CPC title

• A61K31/592

  9,10-Secoergostane derivatives, e.g. ergocalciferol, i.e. vitamin D2 · CPC title

• A61K31/59

  Compounds containing 9, 10- seco- cyclopenta[a]hydrophenanthrene ring systems · CPC title

• A61K31/593

  9,10-Secocholestane derivatives, e.g. cholecalciferol, i.e. vitamin D3 · CPC title