How to Read the Result Report (General DNA Profiling: STR)

The first page of our general DNA profiling result report uses the following expressions for the result statement (using a paternity test as an example).

Positive) A is not excluded as the biological father of B.

Negative) A is excluded as the biological father of B.

Just by looking at this text, it may be difficult for customers to fully understand the test results. In reality, we receive a certain number of inquiries regarding how to read the result report.

When we receive such inquiries, we guide customers to look at the text and the probability of paternity (%) listed in the [Analysis of Test Results] section on the third page of the result report.

We also believe that even among customers who do not contact us, many confirm the results simply by looking at this specific section.

However, as many customers wish to accurately understand how the test results they have were determined, we would like to provide a brief explanation on this page to assist in understanding the result report.

Accurate Understanding of the Results in General DNA Profiling

Accurately understanding the test results of general DNA profiling is nothing other than understanding how to read the attached STR (Short Tandem Repeat) table as a result.

STR refers to a specific region in the DNA base sequence where a short unit of bases is repeated, and the number of repeats varies from person to person. Although briefly stated, this is crucial: STR differs among individuals. This variation among individuals makes it possible to determine blood relations, identify perpetrators in criminal cases, and more.

Generally, these STRs are inherited half from the father and half from the mother. Therefore, we check whether the genotype is shared at all loci from the father or mother. Usually, 13 or more loci are examined, but for simplicity, we will explain using the following table showing about 6 loci.

[Example Table: STR Test Results]

Locus (Loci)	Father A	Child B	Child C
Locus (Loci)D3S1358	Father A15 – 16	Child B15	Child C16
Locus (Loci)vWA	Father A18 – 19	Child B18 – 19	Child C6 – 11
Locus (Loci)D16S539	Father A9 – 12	Child B10 – 12	Child C9 – 10
Locus (Loci)CSF1PO	Father A12 – 13	Child B12 – 13	Child C10 – 11
Locus (Loci)D8S1179	Father A11 – 15	Child B10 - 11	Child C18 - 24
Locus (Loci)D21S11	Father A29 – 30	Child B29	Child C15 - 18

The leftmost column indicates the loci. From the table, you can see how many loci were examined.

To its right are the STR profiling results for Father A, Child B, and Child C.

*The numerical values are listed randomly for explanation purposes. When only one number is written, like 15 for Child B's D3S1358, it indicates having 15 and 15, which means it should be written as 15 – 15 but is abbreviated.

First, let's look at Father A and Child B.

For the top D3S1358 locus, Father A's genotype is 15 and 16, and Child B's is 15, showing they share the STR profile of 15. The numbers shown in red in the table represent the genotype shared by Father A and Child B. Thus, when they share the STR profile at all loci, Father A is determined to be the biological father of Child B.

Next, let's look at Father A and Child C.

For the top D3S1358 locus, Father A's genotype is 15 and 16, and Child C's is 16, showing they share the STR profile of 16. The numbers shown in blue in the table represent the STR profile shared by Father A and Child C. However, looking at the vWA locus directly below, Father A has 18 and 19, and Child C has 6 and 11, indicating completely different STR profiles. When there are multiple loci where the STR profiles are not shared, Father A is determined NOT to be the biological father of Child C.

The above is how to read a general STR table.

In addition to this, if you have any inquiries regarding the result report, please feel free to contact our customer support.

Easy-to-understand explanation of how to read the result report! (Video)

Frequently Asked Questions

Q.What is STR?

STR (Short Tandem Repeat) is a specific part of the DNA sequence where short units of bases are repeated. The number of repeats varies between individuals, which is used for personal identification and DNA testing.

Q.How do you read the STR result table?

The leftmost column shows the analyzed locus. You can check if the genotype is shared between parent and child at each locus to confirm a biological relationship.

Q.What if only one number is listed in the STR table?

If only one number like '15' is listed, it means you have two copies of '15' (homozygous), which should normally be written as '15 - 15' but is abbreviated.

How to Read the Result Report (General DNA Profiling: STR)