Umbilical cord blood stem cell detection and screening system

Abstract

The invention relates to the technical field of genome sequencing, in particular to an umbilical cord blood stem cell detection and screening system.The umbilical cord blood stem cell detection and screening system comprises a collecting and processing unit, a detection and analysis unit and a judgment output unit.The umbilical cord blood is sampled, an umbilical cord blood sample is obtained, and umbilical cord blood stem cells are obtained through automatic processing; the umbilical cord blood stem cell gene segments are sequenced by using a high-throughput sequencing technology, and the sequencing depth and coverage of the umbilical cord blood stem cell gene segments are determined, so that the detection accuracy is improved, the false negative rate is reduced, and a more comprehensive genome region is analyzed; the gene segments of the umbilical cord blood stem cells are automatically analyzed according to the sequencing depth and the coverage degree, a comparison quality score is obtained, whether the gene segments of the umbilical cord blood stem cells are mutated or not is judged according to the comparison quality score, and a judgment result is uploaded to a user interface.

Description

Technical Field

[0001] The present invention relates to the technical field of genome sequencing, and in particular to a detection and screening system for umbilical cord blood stem cells. Background Art

[0002] Genome sequencing is an important technology. Modern genome sequencing technology can sequence a large number of DNA fragments at the same time, which greatly improves experimental efficiency and reduces time and cost. Stem cells (SC) are a type of multipotent cells with self-renewing ability. They are primitive and unspecialized cells. Under certain conditions, they can differentiate into a variety of functional cells and have the potential to regenerate various tissues, organs and the human body. Stem cells exist in all multicellular tissues and can divide into a variety of specialized cells through mitosis and differentiation. They can also use self-renewal to provide more stem cells. There are many sources of stem cells, including umbilical cord blood and bone marrow. For mammals, stem cells are divided into two categories: umbilical cord blood stem cells (Embryonic Stem Cell, ESC) and adult stem cells (Adult Stem Cell, ASC). Umbilical cord blood stem cells are taken from the inner cell mass in the blastocyst, while adult stem cells come from a variety of tissues. Umbilical cord blood stem cells have important medical value, but the existing detection and screening methods are inefficient when performing mutation checks on expected sufficient stem cells. In order to solve this technical problem, we provide a detection and screening system for umbilical cord blood stem cells. Summary of the invention

[0003] The object of the present invention is to provide a detection and screening system for umbilical cord blood stem cells to solve the problems raised in the above-mentioned background technology.

[0004] To achieve the above-mentioned purpose, a detection and screening system for umbilical cord blood stem cells is provided, comprising a collection and processing unit, a detection and analysis unit, and a judgment and output unit;

[0005] The collection and processing unit is used to collect, pack and sample the umbilical cord blood contained in the umbilical cord to obtain the umbilical cord blood sample, and pre-treat the umbilical cord blood sample through automated processing to obtain the umbilical cord blood stem cells;

[0006] The detection and analysis unit introduces high-throughput sequencing technology to divide the gene fragments of the umbilical cord blood stem cells into multiple segments of equal length, and simultaneously sequences the multiple gene fragments of the umbilical cord blood stem cells to determine the sequencing depth and coverage of the gene fragments of the umbilical cord blood stem cells;

[0007] The judgment output unit automatically analyzes the gene fragments of the umbilical cord blood stem cells according to the sequencing depth and coverage, obtains a comparison quality score, and judges whether the gene fragments of the umbilical cord blood stem cells are mutated according to the comparison quality score, and uploads the judgment result to the user interface.

[0008] As a further improvement of the present technical solution, the collection and processing unit uses a quadruple blood collection bag to collect the umbilical cord blood of newborns in a closed manner, and the collected umbilical cord blood is packaged and stored according to different test items, samples are extracted from the packaged umbilical cord blood, and the umbilical cord blood samples are pre-processed through automated processing to obtain umbilical cord blood stem cells.

[0009] As a further improvement of the technical solution, the umbilical cord blood sample is pre-processed by automated processing to obtain umbilical cord blood stem cells, specifically including:

[0010] The collected umbilical cord blood sample is placed in a cell separator based on the centrifugal principle. After starting the centrifugation, it starts with a centrifugal speed of 500 rpm for two minutes to allow the sample to gradually adapt to the centrifugal force. Then the speed is gradually increased to 1800 rpm for ten minutes to promote the effective stratification of different components in the umbilical cord blood. After the main centrifugation stage, the speed is gradually reduced by 200 rpm per minute until it stops to avoid damage to the cells due to sudden stops. The intermediate layer cell suspension of stem cells is automatically collected, and the separated cell suspension is transferred to a cell purification kit. The reagents in the kit interact with the cells and specifically bind to non-stem cell components. The bound impurities are removed by filtration to leave pure umbilical cord blood stem cells.

[0011] As a further improvement of the technical solution, the detection and analysis unit introduces high-throughput sequencing technology to sequence the gene fragments of the umbilical cord blood stem cells to determine the sequencing depth and coverage of the gene fragments of the umbilical cord blood stem cells, specifically including:

[0012] High-throughput sequencers usually require specific library formats and fragment sizes for efficient sequencing. Library construction fragments nucleic acids into appropriate lengths and adds necessary adapters and primer binding sites to make them compatible with the sequencing platform.

[0013] Nucleic acids are extracted from umbilical cord blood stem cells, and the extracted long-chain nucleic acids are randomly cut into fragments of k base pairs in length by ultrasonic fragmentation, and the ends of the fragmented nucleic acids are smoothed by enzymes, and then phosphate groups are added to make the terminal structures complete, and oligonucleotide adapters are connected to both ends of the repaired nucleic acid fragments, wherein the oligonucleotide adapters contain primer binding sites and index sequences required for sequencing, and the library construction is completed, and the constructed library is loaded onto a high-throughput sequencer for sequencing to obtain the total number of sequenced bases of the umbilical cord blood stem cells, and the genome size is determined according to the total number of sequenced bases of the umbilical cord blood stem cells, and the sequencing depth and coverage are calculated from the total number of sequenced bases of the umbilical cord blood stem cells and the genome size. The specific calculation formula for the calculation of the sequencing depth and coverage is:

[0014]

[0015] Where A represents the genome size, B represents the frequency of k-mers of a specific length k counted by sequencing data, and N represents the total number of sequenced bases. is a correction factor, and the k-mer refers to a subsequence of k bases taken continuously from a nucleic acid sequence.

[0016] As a further improvement of the present technical solution, the calculation of sequencing depth and coverage specifically includes:

[0017] The sequencing depth is used to increase the sensitivity of the detection. By increasing the sequencing depth, that is, sequencing a certain site more times, the probability of detecting low-frequency mutations can be increased. Even if the mutation accounts for a small proportion of the sample, sufficient sequencing depth can provide more opportunities to discover these rare mutation events. The coverage is expressed as comprehensive coverage of the genome, so that most regions in the genome can be sequenced. The sequencing depth and coverage are calculated from the total number of sequenced bases of umbilical cord blood stem cells and the genome size. The calculation formula for the sequencing depth is:

[0018]

[0019] Wherein, C represents the sequencing depth, N represents the total number of sequenced bases, A represents the genome size, and the calculation formula of the coverage is:

[0020]

[0021] Where D represents coverage and k represents the number of sequencing reads.

[0022] As a further improvement of the technical solution, the judgment output unit automatically analyzes the sequencing depth and coverage of the gene fragments of the umbilical cord blood stem cells to obtain a comparison quality score, specifically including:

[0023] The base quality value is extracted from the gene fragment of the umbilical cord blood stem cell. The calculation formula of the base quality value is:

[0024] α=-10*log 10 (p)

[0025] Among them, p represents the probability that the base is read incorrectly during sequencing, the base quality mean is set as the base quality threshold, the reads with quality values ​​lower than the threshold are deleted, the adapter sequences at both ends of the sequencing reads are identified and cut off, and the repeated identical reads are deleted to obtain the alignment sequence, and the alignment sequence is aligned with the standard genome extracted from the gene library using the alignment algorithm, and the position of the read on the reference genome and the alignment quality score are recorded. The position is represented by the coordinates on the genome, and the alignment quality score is a numerical indicator used to evaluate the quality of the alignment result between the read and the reference genome.

[0026] As a further improvement of the technical solution, the judgment output unit judges whether the gene fragment of the umbilical cord blood stem cell has a mutation according to the comparison quality score, specifically including:

[0027] The sequencing data of umbilical cord blood stem cells are obtained, and preprocessed and aligned to obtain the alignment quality score of each read segment on the reference genome. The threshold is determined by analyzing the alignment quality scores of a large number of known normal umbilical cord blood stem cell samples. For the umbilical cord blood stem cell gene fragment to be detected, the statistics of the alignment quality scores of all the read segments it contains are calculated. If the alignment quality score statistic of the gene fragment is lower than the set threshold, it is determined that the gene fragment has a mutation.

[0028] As a further improvement of the technical solution, if the comparison quality score statistic of the gene fragment is lower than a set threshold, it is determined that the gene fragment has a mutation, specifically including:

[0029] The standard genome sequence is defined as R, the alignment sequence is defined as S, and a score function Q is defined (i) represents the quality score of the i-th position in the aligned sequence. For each gene fragment position i, the standard genome sequence R is calculated. (i) and the alignment sequence S (i) The matching score M (i) :

[0030]

[0031] For insertions and deletions, define the insertion penalty I (i) and missing penalty Y (i) , if a new base is inserted into the sequence at position i, and the insertion penalty score is set to -2, then I (i) = -2, otherwise I (i)=0, if the sequence is missing a base at position i, the missing penalty score is set to -2, then Y (i) = -2, otherwise Y (i) = 0, the matching score, insertion penalty and missing penalty are calculated comprehensively to obtain the score V of position i (i) :

[0032] V (i) =M (i) +I (i) +Y (i)

[0033] Score all positions of the alignment sequence to get a total score T:

[0034]

[0035] Set the threshold T YZ , if T<T YZ , it means that there is a mutation in the aligned sequence. For each position with a negative score, it is marked as a mutation position, and the total score T and mutation position of the aligned sequence are sent to the user interface.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] In the umbilical cord blood stem cell detection and screening system, the collection and processing unit obtains umbilical cord blood stem cells by collecting, packaging, sampling and pre-processing the umbilical cord blood contained in the umbilical cord, which is beneficial to maintaining the activity and function of the cells. The detection and analysis unit simultaneously sequences gene fragments through high-throughput sequencing technology, which improves the detection efficiency, quickly determines the sequencing depth and coverage of gene fragments, improves the accuracy of detection, reduces the false negative rate, and ensures that more comprehensive genomic regions are analyzed. The judgment output unit automatically analyzes the gene fragments of umbilical cord blood stem cells according to the sequencing depth and coverage to determine whether the gene fragments of umbilical cord blood stem cells are mutated. It can quickly process large amounts of data, significantly shorten the analysis cycle, more accurately identify potential mutation areas, and reduce the risk of missed detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 It is an overall block diagram of the present invention.

[0039] The meaning of each number in the figure is:

[0040] 1. Acquisition and processing unit; 2. Detection and analysis unit; 3. Judgment and output unit. DETAILED DESCRIPTION

[0041] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0042] Example 1

[0043] The present invention provides a detection and screening system for umbilical cord blood stem cells. Figure 1 As shown, it includes a collection and processing unit 1, a detection and analysis unit 2, and a judgment and output unit 3;

[0044] The collection and processing unit 1 is used to collect, pack and sample the umbilical cord blood contained in the umbilical cord to obtain the umbilical cord blood sample, and pre-treat the umbilical cord blood sample through automated processing to obtain the umbilical cord blood stem cells;

[0045] The collection and processing unit 1 uses a quadruple blood collection bag to collect the umbilical cord blood of newborns in a closed manner, packages and stores the collected umbilical cord blood according to different test items, extracts samples from the packaged umbilical cord blood, and pre-treats the umbilical cord blood samples through automated processing to obtain umbilical cord blood stem cells;

[0046] The umbilical cord blood samples are pre-processed by automated processing to obtain umbilical cord blood stem cells, including:

[0047] The collected umbilical cord blood sample is placed in a cell separator based on the centrifugal principle. After starting the centrifugation, it starts with a centrifugal speed of 500 rpm for two minutes to allow the sample to gradually adapt to the centrifugal force. Then the speed is gradually increased to 1800 rpm for ten minutes to promote the effective stratification of different components in the umbilical cord blood. After the main centrifugation stage, the speed is gradually reduced by 200 rpm per minute until it stops to avoid damage to the cells due to sudden stops. The middle layer cell suspension of stem cells is automatically collected and the separated cell suspension is transferred to the cell purification kit. The reagents in the kit interact with the cells and specifically bind to the non-stem cell components. The bound impurities are removed by filtration to leave pure umbilical cord blood stem cells.

[0048] The detection and analysis unit 2 introduces high-throughput sequencing technology to divide the gene fragments of the umbilical cord blood stem cells into multiple segments of equal length, and simultaneously sequences the multiple gene fragments of the umbilical cord blood stem cells to determine the sequencing depth and coverage of the gene fragments of the umbilical cord blood stem cells;

[0049] The detection and analysis unit 2 introduces high-throughput sequencing technology to sequence the gene fragments of the umbilical cord blood stem cells, and determines the sequencing depth and coverage of the gene fragments of the umbilical cord blood stem cells, specifically including:

[0050] High-throughput sequencers usually require specific library formats and fragment sizes for efficient sequencing. Library construction fragments nucleic acids into appropriate lengths and adds necessary adapters and primer binding sites to make them compatible with the sequencing platform;

[0051] Nucleic acids are extracted from umbilical cord blood stem cells, and the extracted long-chain nucleic acids are randomly cut into fragments of k base pairs in length by ultrasonic fragmentation, and the ends of the fragmented nucleic acids are smoothed by enzymes, and then phosphate groups are added to make the terminal structures complete, and oligonucleotide adapters are connected to both ends of the repaired nucleic acid fragments. The oligonucleotide adapters contain primer binding sites and index sequences required for sequencing, and the library construction is completed. The constructed library is loaded onto a high-throughput sequencer for sequencing to obtain the total number of sequenced bases of the umbilical cord blood stem cells, and the genome size is determined according to the total number of sequenced bases of the umbilical cord blood stem cells. The sequencing depth and coverage are calculated from the total number of sequenced bases of the umbilical cord blood stem cells and the genome size. The specific calculation formula for the calculation of sequencing depth and coverage, and genome size is:

[0052]

[0053] Where A represents the genome size, B represents the frequency of k-mers of a specific length k counted by sequencing data, and N represents the total number of sequenced bases. is the correction factor, and k-mer refers to a subsequence of length k bases taken continuously from a nucleic acid sequence;

[0054] Calculation of sequencing depth and coverage, including:

[0055] Sequencing depth is used to increase the sensitivity of detection. By increasing the sequencing depth, that is, sequencing a certain site more times, the probability of detecting low-frequency mutations can be increased. Even if the mutation accounts for a small proportion of the sample, sufficient sequencing depth can provide more opportunities to discover these rare mutation events. Coverage is expressed as comprehensive coverage of the genome, so that most areas of the genome can be sequenced. Sequencing depth and coverage are calculated from the total number of sequenced bases and genome size of umbilical cord blood stem cells. The calculation formula for sequencing depth is:

[0056]

[0057] Among them, C represents the sequencing depth, N represents the total number of sequenced bases, A represents the genome size, and the calculation formula for coverage is:

[0058]

[0059] Where D represents coverage and k represents the number of sequencing reads.

[0060] The judgment output unit 3 automatically analyzes the gene fragments of the umbilical cord blood stem cells according to the sequencing depth and coverage, obtains a comparison quality score, and judges whether the gene fragments of the umbilical cord blood stem cells are mutated according to the comparison quality score, and uploads the judgment result to the user interface;

[0061] The judgment output unit automatically analyzes the sequencing depth and coverage of the gene fragments of the umbilical cord blood stem cells to obtain a comparison quality score, which specifically includes:

[0062] The base quality value is extracted from the gene fragments of umbilical cord blood stem cells. The calculation formula of the base quality value is:

[0063] α=-10*log 10 (p)

[0064] Among them, p represents the probability that the base is read incorrectly during sequencing, the base quality mean is set as the base quality threshold, the reads with quality values ​​below the threshold are deleted, the adapter sequences at both ends of the sequencing reads are identified and cut off, and the repeated identical reads are deleted to reduce the deviation of subsequent analysis, and the alignment sequence is obtained. The alignment sequence is aligned with the standard genome using the alignment algorithm. The standard genome is extracted from the gene library, and the position of the read on the reference genome and the alignment quality score are recorded. The position is represented by the coordinates on the genome, such as the chromosome number and the start and end base positions on the chromosome. By recording these positions, we can know the relative position of the sequencing read in the entire genome. For example, if a read matches the region starting from the 1000th base to the 1500th base on chromosome 1 of the reference genome, then the recorded position information is "chr1: 1000-1500". The alignment quality score is a numerical indicator used to evaluate the quality of the alignment result of the read segment with the reference genome. It is calculated by assigning different scores to matches, mismatches, insertions and deletions, etc.:

[0065] For example, if the match score is +1, the mismatch score is -1, and the insertion and deletion score is -2, the reference sequence is: ATGCG, and the sequencing read segment is: ATGCA, then the alignment quality score is:

[0066] β=3e*1+e'*(-1)

[0067] Among them, β is the alignment quality score, e represents a match, and e' represents a mismatch.

[0068] The judgment output unit judges whether the gene fragment of the umbilical cord blood stem cell has a mutation according to the comparison quality score, specifically including:

[0069] Acquire the sequencing data of umbilical cord blood stem cells, perform preprocessing and alignment, obtain the alignment quality score of each read segment on the reference genome, determine the threshold by analyzing the alignment quality scores of a large number of known normal umbilical cord blood stem cell samples, and calculate the statistics of the alignment quality scores of all read segments contained in the umbilical cord blood stem cell gene fragment to be detected. If the alignment quality score statistic of the gene fragment is lower than the set threshold, it is determined that the gene fragment has a mutation;

[0070] If the comparison quality score statistic of a gene fragment is lower than the set threshold, the gene fragment is judged to have a mutation, including:

[0071] The standard genome sequence is defined as R, the alignment sequence is defined as S, and a score function Q is defined (i) represents the quality score of the i-th position in the aligned sequence. For each gene fragment position i, the standard genome sequence R is calculated. (i) and the alignment sequence S (i) The matching score M (i) :

[0072]

[0073] For insertions and deletions, define the insertion penalty I (i) and missing penalty Y (i) , if a new base is inserted into the sequence at position i, and the insertion penalty score is set to -2, then I (i) = -2, otherwise I (i) =0, if the sequence is missing a base at position i, the missing penalty score is set to -2, then Y (i) = -2, otherwise Y (i) = 0, the matching score, insertion penalty and missing penalty are calculated comprehensively to obtain the score V of position i (i) :

[0074] V (i) =M (i) +I (i) +Y (i)

[0075] Score all positions of the alignment sequence to get a total score T:

[0076]

[0077] Set the threshold T YZ , if T<T YZ , it means that there is a mutation in the aligned sequence. For each position with a negative score, it is marked as a mutation position, and the total score T and mutation position of the aligned sequence are sent to the user interface.

[0078] In the present invention, the collection and processing unit obtains umbilical cord blood stem cells by collecting, packaging, sampling and pre-processing the umbilical cord blood contained in the umbilical cord, which is beneficial to maintaining the activity and function of the cells. The detection and analysis unit simultaneously sequences the gene fragments through high-throughput sequencing technology, which improves the detection efficiency, quickly determines the sequencing depth and coverage of the gene fragments, improves the accuracy of the detection, reduces the false negative rate, and ensures that more comprehensive genome regions are analyzed. The judgment output unit automatically analyzes the gene fragments of the umbilical cord blood stem cells according to the sequencing depth and coverage, and determines whether the gene fragments of the umbilical cord blood stem cells are mutated. It can quickly process a large amount of data, significantly shorten the analysis cycle, more accurately identify potential mutation areas, and reduce the risk of missed detection.

[0079] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. The above embodiments and descriptions are only preferred examples of the present invention and are not intended to limit the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A detection and screening system for umbilical cord blood stem cells, characterized in that: It comprises a collection and processing unit (1), a detection and analysis unit (2), and a judgment and output unit (3); The collection and processing unit (1) is used to collect, package and sample the umbilical cord blood contained in the umbilical cord to obtain an umbilical cord blood sample, and to pre-treat the umbilical cord blood sample through automated processing to obtain umbilical cord blood stem cells; The detection and analysis unit (2) introduces high-throughput sequencing technology to divide the gene fragments of the umbilical cord blood stem cells into multiple segments of equal length, and simultaneously sequences the multiple gene fragments of the umbilical cord blood stem cells to determine the sequencing depth and coverage of the gene fragments of the umbilical cord blood stem cells; The judgment output unit (3) automatically analyzes the gene fragments of the umbilical cord blood stem cells according to the sequencing depth and coverage, obtains a comparison quality score, and judges whether the gene fragments of the umbilical cord blood stem cells are mutated according to the comparison quality score, and uploads the judgment result to the user interface.

2. The umbilical cord blood stem cell detection and screening system according to claim 1, characterized in that: The collection and processing unit (1) uses a quadruple blood collection bag to collect the umbilical cord blood of newborns in a closed manner, packages and stores the collected umbilical cord blood according to different test items, extracts samples from the packaged umbilical cord blood, and pre-treats the umbilical cord blood samples through automated processing to obtain umbilical cord blood stem cells.

3. The umbilical cord blood stem cell detection and screening system according to claim 2, characterized in that: The pre-processing of the umbilical cord blood sample by automated processing to obtain umbilical cord blood stem cells specifically includes: The collected umbilical cord blood sample is placed in a cell separator based on the centrifugal principle. After the centrifugation is started, it starts with a centrifugal speed of 500 rpm for two minutes, and then gradually increases to 1800 rpm for ten minutes. After the main centrifugation stage, the speed is reduced by 200 rpm per minute until it stops. The middle layer cell suspension of stem cells is automatically collected and the separated cell suspension is transferred to a cell purification kit. The reagents in the kit interact with the cells and specifically bind to non-stem cell components. The bound impurities are removed by filtration to leave pure umbilical cord blood stem cells.

4. The umbilical cord blood stem cell detection and screening system according to claim 3, characterized in that: The detection and analysis unit (2) introduces high-throughput sequencing technology to sequence the gene fragments of the umbilical cord blood stem cells, and determines the sequencing depth and coverage of the gene fragments of the umbilical cord blood stem cells, specifically including: Nucleic acids are extracted from umbilical cord blood stem cells, and the extracted long-chain nucleic acids are randomly cut into fragments of k base pairs in length by ultrasonic fragmentation, and the ends of the fragmented nucleic acids are smoothed by enzymes, and then phosphate groups are added, and oligonucleotide adapters are connected to both ends of the repaired nucleic acid fragments to complete library construction, and the constructed library is loaded onto a high-throughput sequencer for sequencing to obtain the total number of sequenced bases of the umbilical cord blood stem cells, and the genome size is determined according to the total number of sequenced bases of the umbilical cord blood stem cells, and the sequencing depth and coverage are calculated from the total number of sequenced bases of the umbilical cord blood stem cells and the genome size. The specific calculation formula for the calculation of the sequencing depth and coverage is: Where A represents the genome size, B represents the frequency of k-mers of a specific length k counted by sequencing data, and N represents the total number of sequenced bases. is a correction factor, and the k-mer refers to a subsequence of k bases taken continuously from a nucleic acid sequence.

5. The umbilical cord blood stem cell detection and screening system according to claim 4, characterized in that: The calculation of sequencing depth and coverage specifically includes: The sequencing depth and coverage are calculated from the total number of sequenced bases and genome size of the umbilical cord blood stem cells. The calculation formula for the sequencing depth is: Wherein, C represents the sequencing depth, N represents the total number of sequenced bases, A represents the genome size, and the calculation formula of the coverage is: Where D represents coverage and k represents the number of sequencing reads.

6. The umbilical cord blood stem cell detection and screening system according to claim 3, characterized in that: The judgment output unit (3) automatically analyzes the sequencing depth and coverage of the gene fragments of the umbilical cord blood stem cells to obtain a comparison quality score, specifically including: The base quality value is extracted from the gene fragment of the umbilical cord blood stem cell. The calculation formula of the base quality value is: α=-10*log 10 (p) Among them, p represents the probability that the base is read incorrectly during sequencing, the base quality mean is set as the base quality threshold, the reads with quality values ​​lower than the threshold are deleted, the adapter sequences at both ends of the sequencing reads are identified and cut off, and the repeated identical reads are deleted to obtain the alignment sequence, and the alignment sequence is aligned with the standard genome extracted from the gene library using the alignment algorithm, and the position of the read on the reference genome and the alignment quality score are recorded. The position is represented by the coordinates on the genome, and the alignment quality score is a numerical indicator used to evaluate the quality of the alignment result between the read and the reference genome.

7. The umbilical cord blood stem cell detection and screening system according to claim 3, characterized in that: The judgment output unit (3) judges whether a mutation occurs in the gene fragment of the umbilical cord blood stem cell according to the comparison quality score, specifically comprising: The sequencing data of umbilical cord blood stem cells are obtained, and preprocessed and aligned to obtain the alignment quality score of each read segment on the reference genome. The threshold is determined by analyzing the alignment quality scores of a large number of known normal umbilical cord blood stem cell samples. For the umbilical cord blood stem cell gene fragment to be detected, the statistics of the alignment quality scores of all the read segments it contains are calculated. If the alignment quality score statistic of the gene fragment is lower than the set threshold, it is determined that the gene fragment has a mutation.

8. The umbilical cord blood stem cell detection and screening system according to claim 7, characterized in that: If the comparison quality score statistic of the gene fragment is lower than the set threshold, it is determined that the gene fragment has a mutation, specifically including: The standard genome sequence is defined as R, the alignment sequence is defined as S, and a score function Q is defined (i) represents the quality score of the i-th position in the aligned sequence. For each gene fragment position i, the standard genome sequence R is calculated. (i) and the alignment sequence S (i) The matching score M (i) : For insertions and deletions, define the insertion penalty I (i) and missing penalty Y (i) , if a new base is inserted into the sequence at position i, and the insertion penalty score is set to -2, then I (i) = -2, otherwise I (i) =0, if the sequence is missing a base at position i, the missing penalty score is set to -2, then Y (i) = -2, otherwise Y (i) = 0, the matching score, insertion penalty and missing penalty are calculated comprehensively to obtain the score V of position i (i) : V (i) =M (i) +I (i) +Y (i) Score all positions of the alignment sequence to get a total score T: Set the threshold T YZ , if T <T YZ , it means that there is a mutation in the aligned sequence. For each position with a negative score, it is marked as a mutation position, and the total score T and mutation position of the aligned sequence are sent to the user interface.

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