Combo DNA Ancestry Test

Mitochondrial DNA (mtDNA) is the circular DNA which is found in the mitochondria of human cells. Each cell can contain several mitochondria and each mitochondrion contains dozens of copies of the 16,569 base pairs of mtDNA so in every cell there can be thousands of copies of mtDNA. This differs from only two copies per cell of the linear and much larger nuclear genome of 3.3 billion base pairs, which includes the autosomal and sex chromosomes. Each individual inherits mtDNA from only their mother, hence there is no recombination (mixing) of the mtDNA from generation to generation. This ensures that mtDNA essentially remains unchanged through the maternal line, providing an incredibly useful way to trace maternal ancestry.

The circular mitochondrial genome has three regions – two small hypervariable (HVR) regions and a large coding region. Most of the variation in the mtDNA occurs in the non-coding HVR regions, as this variation does not affect the function of any proteins etc. The mtDNA sequencing available here can sequence just the HVR1 region, both hypervariable regions (HVR1 and HVR2) or the complete mitochondrial genome (HVR1, HVR2 and the coding region). If two individuals have a perfect match at their HVR1 and HVR2 regions, further comparison of the much larger coding region can provide a higher stringency comparison and further resolution. The coding region covers the remainder of the mitochondrial genome and the complete mitochondrial genome is 16,569 base pairs.

The mtDNA sequencing analysis uses a technique called Sanger sequencing to determine the DNA sequence in the specified region of the mtDNA. The entire DNA sequence for each region tested is provided to you in your mtDNA test report. If you choose to test all three regions (HVR1, HVR2 and coding region), you will receive a reading on all 16,569 base pairs of your mtDNA. If only one or both hypervariable regions are sequenced, a shorter reading will be provided. Your mtDNA sequencing results are also compared to a reference sequence called “rCRS” (revised Cambridge Reference Sequence) and all of the positions within your mtDNA which differ from rCRS are listed in your report.

Your unique mtDNA sequence result is known as your mtDNA profile. Individuals share the same mtDNA profile if their mtDNA sequences are an exact match to each other. Since mtDNA is passed down from mother to child along the direct maternal lineage, individuals who have descended from the same maternal lineage are expected to have exactly the same or very similar mtDNA profiles. If two individuals have different mtDNA profiles, it would conclusively confirm that they did not descend from the same maternal lineage, regardless of family legend.

Y-DNA refers to the DNA on the male sex chromosome – the Y chromosome. We each have 23 pairs of chromosomes: 22 pairs of autosomal chromosomes and two sex chromosomes – the X and Y chromosomes. Females inherit an X chromosomes from each parent (but no Y chromosome), while males inherit an X chromosome from their mother and a Y chromosome from their father. Very little recombination (mixing) occurs between the X and Y chromosomes in males, hence the Y-DNA essentially remains unchanged through the paternal line, providing an incredibly useful way to trace paternal ancestry.

The Y-DNA STR test is a useful technique used in ancestry, relationship and forensic applications. The test analyzes markers in the Y chromosome known as STRs or ‘short tandem repeats’. STR markers are short segments of DNA (2-13 nucleotides in length), which are repeated multiple times. STR analyses measure the exact number of repeat units. The number of repeats differs between individuals because STRs change frequently. The more closely related two individuals are along their direct paternal line, the more similar their Y-DNA STR profiles will be. Y-DNA STR tests can be used for forensic applications, investigating relationships, tracing distant male relatives who may have descended from the same paternal lineage and identifying links to famous people. It is a simple test that can provide you with rich information about your paternal lineage.

The Y-DNA STR Marker test uses a technique called polymerase chain reaction (PCR) to examine a defined set of STR markers in your Y-DNA. This technique determines the number of repeats at each marker tested – either 20, 44 or 101 markers, depending on the requested analysis.

When two individuals take the Y-DNA STR marker test, their STR numbers can be compared to see if there is a match. The confidence with which the Y-DNA STR test can predict a relationship between two individuals increases as more STR markers are tested. A calculation called “TMRCA” (time to most recent common ancestor) can be performed to estimate how many generations ago the two males likely shared a common paternal ancestor. Comparing more Y-DNA STR markers will provide a higher stringency comparison and a more precise TMRCA calculation.