Clinical method for the genetic screening of newborns using tandem mass spectrometry

• US 7,531,364 B2
• Filed: 09/13/2005
• Issued: 05/12/2009
• Est. Priority Date: 01/30/1999
• Status: Expired due to Fees

• Current Assignee: PerkinElmer Genetics, Inc. (Revvity, Inc.)
• Original Assignee: PerkinElmer Genetics, Inc. (Revvity, Inc.)
• Inventors: Chace, Donald H.
• Primary Examiner(s): Gakh; Yelena G
• Assistant Examiner(s): Xu; Robert
• Application Number:
  US11/225,615
• Publication Number:
  US 20060014297A1
• Time in Patent Office: 1,337 Days
• Field of Search: None
• US Class Current: 436/173
• CPC Class Codes: G01N 2800/02 Nutritional disorders
• CPC Class Codes: G01N 33/6848 Methods of protein analysis involving mass spectrometry
• CPC Class Codes: G01N 33/92 involving lipids, e.g. cholesterol , lipoproteins, or their receptors steroid hormones G01N33/743
• CPC Class Codes: H01J 49/0036 Step by step routines describing the handling of the data generated during a measurement
• CPC Class Codes: Y10T 436/10 Composition for standardization, calibration, simulation, stabilization, preparation or preservation; processes of use in preparation for chemical testing
• CPC Class Codes: Y10T 436/24 Nuclear magnetic resonance, electron spin resonance or other spin effects or mass spectrometry

Abstract

A method for screening newborns using electrospray tandem mass spectrometry. The method improves the current protocols that use tandem mass spectrometry by assuring accurate and consistent results at the clinical level through enhanced quality controls and quality assurance protocols as applied to the scan profiling and sample preparation of blood spots from newborns. Specific additives are used in precise concentrations of internal standards, employing detailed controls adapted to distinguish twenty metabolites, which are scanned and vigorously compared to known spectra results. Revealing peaks, metabolite concentration, and scan intensities in the quality assurance steps are then compared to a range of thresholds to determine whether or not the sample is contaminated, drug-ridden, diagnosable, or unacceptable. All spectra results and quality assurance flags are organized in spreadsheet form and exported to a database where values are compiled and stored for daily output results and trend analysis. The method provides for high-throughput and quality results, having a consistent predictability for genetically testing newborns efficiently and accurately.

Claims

1. A method of screening newborns, the method comprising:

scanning samples comprising an internal standard and blood extract from a blood spot obtained from a newborn, said scanning performed using an electrospray tandem mass spectrometer to obtain sample concentration data;

obtaining results of control blood samples scanned using an electrospray tandem mass spectrometer, said control blood samples having at least one marker therein; and

comparing concentration data and the results of control blood samples scanned to determine the quality of said sample based upon whether information within said concentration data is recognized as corresponding to said marker.

2. The method of claim 1 wherein said marker comprises an exogenous substance.

3. The method of claim 2 wherein said marker comprises a blood anti-coagulant.

4. The method of claim 2 wherein said control blood sample comprises hemolyzed blood.

5. The method of claim 1 wherein said control blood sample comprises hemolyzed blood.

6. The method of claim 2 wherein said internal standard comprises a free carnitine/acylcarnitine standard.

7. The method of claim 6, wherein said free carnitine/acylcarnitine standard comprises an internal standard preparation comprising ²H₉-carnitine, ²H₃-acetylcarnitine, ²H₃-propionylcarnitine, ²H₃-butyrylcarnitine, ²H₉-isovalerylcarnitine, ²H₃-octanoylcamitine, ²H₉-myristoylcarnitine, and ²H₃-palmitoylcarnitine.

8. The method of claim 7 wherein said internal standard further comprises an amino acid standard.

9. The method of claim 8, wherein said amino acid standard comprising ¹⁵N¹³C-Glycine, ²H₄-Alanine, ²H₈-Valine, ²H₃-Leucine, ²H₃-Methionine, ²H₅-Phenylalanine, ²H₄-Tyrosine, ²H₃-Aspartate, ²H₃-Glutarnate, ²H₂-Ornithine-²HCl, ²H₂-Citrulline, and ²H₄¹³C-Mginine-HCl.

10. The method of claim 1, further comprising the steps of:

organizing scan results by means of spreadsheet;

inputting said scan results into a database adapted to assist in organizing, recognizing, and interpreting said scan data;

assigning said scan results with demographic data of each of said newborns corresponding to each of said samples; and

flagging each of said samples that reveal an abnormality, thereby forming a plurality of flagged samples, wherein each of said flagged samples can be interpreted using a reference guide, and wherein a next course of action can be taken for each of said flagged samples.

11. The method of claim 1, wherein for the step of scanning said samples, a free carnitine MRM scan function is implemented.

12. The method of claim 11, wherein said free carnitine MRM scan function implements quality assurance data for acylcarnitine hydrolysis.

13. The method of claim 12, wherein said quality assurance data for acylcamitine hydrolysis is a dual mass peak seen around 221.3/103.1 atomic mass units.

14. The method of claim 1, wherein for the step of scanning said samples an acetylcarnitine MRM scan function is implemented.

15. The method of claim 14, wherein said acetylcarnitine MRM scan function implements quality assurance data for glutamate hydrolysis.

16. The method of claim 15, wherein said quality assurance data for glutamate hydrolysis is a dual mass peak seen around 261.3/85.1 atomic mass units.

17. The method of claim 1, wherein for the step of scanning said samples, an acylcarnitine full scan is implemented.

18. The method of claim 1, wherein for the step of scanning said samples, an amino acid full scan is implemented.

19. The method of claim 18, wherein said amino acid full scan implements quality assurance data for amino acid detection accuracy.

20. The method of claim 19, wherein said quality assurance data for amino acid detection accuracy is a concentration value corresponding to an amount of marker not normally found in blood.

21. The method of claim 1, wherein for the step of scanning said samples, a basic amino acid MRM is implemented.

22. The method of claim 21, wherein said basic amino acid MRM includes quality assurance data for citrulline.

23. The method of claim 22, wherein said quality assurance data for citrulline is a peak seen around a dual mass value of 232.3/113.1 atomic mass units.

24. A method of screening newborns, the method comprising:

receiving a plurality of blood spots;

obtaining an internal standard comprising at least one labeled compound;

preparing a plurality of samples comprising;

said internal standard and a blood extract from one of said blood spots;

scanning said plurality of samples using an electrospray tandem mass spectrometer to produce scan results;

scanning a plurality of control blood samples having a marker therein to produce control sample results;

scanning a plurality of standards comprising said at least one labeled compound to produce a plurality of standard results;

comparing said control sample results to said plurality of standard results; and

analyzing said scan results to determine the quality of said scan results.

25. The method of claim 24 wherein said marker comprises an exogenous substance.

26. The method of claim 25 wherein said marker comprises a blood anticoagulant.

27. The method of claim 25 wherein said control blood sample comprises hemolyzed blood.

28. The method of claim 24 wherein said control blood samples comprises hemolyzed blood.

29. The method of claim 24, wherein said internal standard comprises a free carnitine/acylcamitine standard.

30. The method of claim 29, wherein said free carnitine/acylcamitine standard comprises an amino acid standard comprising ²H₉-carnitine, ²H₃-acetylcarnitine, ²H₃-propionylcarnitine, ²H₃-butyrylcarnitine, ²H₉-isovalerylcarnitine, ²H₃-octanoylcarnitine, ²H₉-myristoylcarnitine, and ²H₃-palmitoylcarnitine.

31. The method of claim 24 wherein said internal standard further comprises an amino acid standard.

32. The method of claim 31, wherein said amino acid standard comprising ¹⁵N¹³C-Glycine, ²H₄-Alanine, ²H₈-Valine, ²H₃-Leucine, ²H₃-Methionine, ²H₅-Phenylalanine, ²H₄-Tyrosine, ²H₃-Aspartate, ²H₃-Glutamate, ²H₂-Ornithine-²HCl, ²H₂-Citrulline, and ²H₄¹³C-Arginine-HCl.