DNA analysis system

• US 20020127566A1
• Filed: 08/30/2001
• Published: 09/12/2002
• Est. Priority Date: 01/18/2001
• Status: Active Grant

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Huang, Min, Hirabayashi, Atsumu, Hirabayashi, Yukiko, Okumura, Akihiko
• Granted Patent: US 6,673,547 B2
• Time in Patent Office: Days
• US Class Current: 435/6
• CPC Class Codes: C12Q 1/6827 for detection of mutation or polymorphism
• CPC Class Codes: C12Q 1/6872 involving mass spectrometry
• CPC Class Codes: C12Q 2565/627 being a mass spectrometer
• CPC Class Codes: H01J 49/10 Ion sources; Ion guns

Abstract

A genome DNA analysis method and a genome DNA analysis system of the present invention generates multiply-charged ions with 5 or more electric charges by an ionization process using air atomization. Also, a mass spectrometric spectrum thereof is detected and compared with predicted mass spectrum patterns in the presence or absence of polymorphism to determine a base at a polymorphic point.

Claims

1. A DNA analysis system for analyzing DNA polymorphism, comprising:

ionization means for generating plural kinds of multiply-charged ions of a test DNA fragment, where each of them has five or more charges;

mass spectrometric means for performing a mass spectrometry on the multiply-charged ion formed by the ionization means;

analyzing-result prediction means that predicts a mass spectrum pattern from the mass spectrometric means in each of two cases, where one is that the test DNA fragment is polymorphic and the other is that the test DNA fragment is not polymorphic, based on both information about the test DNA fragment and information about a polymorphism point;

comparative processing means for comparing a plurality of the mass spectrum patterns predicted by the analyzing-result prediction means with the analyzing results of the test DNA fragment analyzed by the mass spectrometric means to determine a nucleic acid base on the polymorphism point.

2. The DNA analysis system according to claim 1, wherein

the analyzing-result prediction means predicts a mass-to-charge ratio (m/z;

m is an ion mass, z is the number of electric charges) of the plural kinds of multi-charged ions in each of two cases, where one is that the test DNA fragment is polymorphic and the other is that the test DNA fragment is not polymorphic.

3. The DNA analysis system according to claim 1, wherein

the analyzing-result prediction means predicts a mass-to-charge ratio (m/z;

m is an ion mass, z is the number of electric charges) of the plural kinds of multi-charged ions and a distribution of ion intensities in each of two cases, where one is that the test DNA fragment is polymorphic and the other is that the test DNA fragment is not polymorphic.

4. The DNA analysis system according to claim 1, further comprising:

sampling means for supplying a sample including test DNA fragments to the ionization means at fixed intervals; and

detecting-output analysis means for subtracting a mass spectrum obtained as an analyzing result with respect to a sample previously measured and modified by weight from a mass spectrum obtained as a detecting-output of the mass spectrometric means, wherein

the mass spectrum processed by the detecting-output analysis means is provided as an analyzing result with respect to the test DNA fragment in the sample.

5. The DNA analysis system according to claim 1, wherein

the ionization means generates multiply-charged ions of the test DNA fragment by the ionization means using an air atomization.

6. The DNA analysis system according to claim 1, wherein a nucleic acid base of a single nucleotide polymorphism point in the test DNA fragment is specified.

7. The DNA analysis system according to claim 4, further comprising:

display means for displaying the occurrence of an emergency when a maximum ion intensity detected by the mass spectrometric means is smaller than a predetermined threshold.

8. The DNA analysis system according to claim 7, further comprising:

communication means for sending information about the occurrence of the emergency to a system administrator.

9. The DNA analysis system according to claim 4, wherein

the sampling means introduces a standard sample into the ionization means when a maximum ion intensity of the mass spectrum detected by the mass spectrometric means is smaller than a predetermined threshold.

10. The DNA analysis system according to claim 9, wherein

when a maximum ion intensity of a mass spectrum of the standard sample detected by the mass spectrometric means is equal to or higher than the threshold, the sample where the maximum ion intensity of the mass spectrum is detected as one smaller than the threshold is re-supplied to the ionization means by the sampling means.

11. The DNA analysis system according to claim 9, further comprising:

a plurality of measurement systems, where each of the measurement systems comprises the sampling means, the ionization means, and the mass spectrometric means, wherein

when a maximum ion intensity of a mass spectrum of the standard sample detected by mass spectrometric means in one measurement system of the plurality of measurement systems is smaller than the threshold, the sample where a maximum ion intensity is detected as one smaller than the threshold at the one measurement system is transmitted to sampling means of another measurement system except the one measurement system.

12. The DNA analysis system according to claim 9, further comprising:

a plurality of measurement systems, where each of the measurement systems comprises the sampling means, the ionization means, and the mass spectrometric means, wherein

when a maximum ion intensity of a mass spectrum of the standard sample detected by mass spectrometric means in one measurement system of the plurality of measurement systems is smaller than the threshold, a sample intended to be measured by the one measurement system is sent to sampling means of another measurement system except the one measurement system.