AncestryDNA offers a direct-to-consumer genealogical DNA test. Consumers provide a sample of their DNA to the company for analysis. AncestryDNA then uses DNA sequences to infer family relationships with other Ancestry DNA users and to provide what it calls an "ethnicity estimate". Previously, also offered paternal Y-chromosome DNA and maternal mitochondrial DNA tests, but those were discontinued in June 2014. The company describes the technical process of testing in a scientific white paper. In May 2019 the company claimed that their database contained 15 million completed DNA kits bought by customers.


chromosomal misalignmentMM-phase
It is thought that unattached or improperly attached kinetochores generate a signal to prevent premature progression to anaphase, even if most of kinetochores have been attached and most of the chromosomes have been aligned. Such a signal creates the mitotic spindle checkpoint. This would be accomplished by regulation of the anaphase-promoting complex, securin, and separase. The analysis of metaphase chromosomes is one of the main tools of classical cytogenetics and cancer studies. Chromosomes are condensed (thickened) and highly coiled in metaphase, which makes them most suitable for visual analysis. Metaphase chromosomes make the classical picture of chromosomes (karyotype).


mitoticmitosesmitotic division
Endoreduplication (or endoreplication) occurs when chromosomes duplicate but the cell does not subsequently divide. This results in polyploid cells or, if the chromosomes duplicates repeatedly, polytene chromosomes. Endoreduplication is found in many species and appears to be a normal part of development. Endomitosis is a variant of endoreduplication in which cells replicate their chromosomes during S phase and enter, but prematurely terminate, mitosis. Instead of being divided into two new daughter nuclei, the replicated chromosomes are retained within the original nucleus. The cells then re-enter G 1 and S phase and replicate their chromosomes again.

Chromosome 2

2human chromosome 2Chromosome 2 (human)
The closest human relative, the chimpanzee, has nearly identical DNA sequences to human chromosome 2, but they are found in two separate chromosomes. The same is true of the more distant gorilla and orangutan. The presence of a vestigial centromere. Normally a chromosome has just one centromere, but in chromosome 2 there are remnants of a second centromere in the q21.3–q22.1 region. The presence of vestigial telomeres. These are normally found only at the ends of a chromosome, but in chromosome 2 there are additional telomere sequences in the q13 band, far from either end of the chromosome. 2p15-16.1 microdeletion syndrome. Autism. Alport syndrome. Alström syndrome.


The second way bacteria transfer genetic material is by transduction, when the integration of a bacteriophage introduces foreign DNA into the chromosome. Many types of bacteriophage exist, some simply infect and lyse their host bacteria, while others insert into the bacterial chromosome. Bacteria resist phage infection through restriction modification systems that degrade foreign DNA, and a system that uses CRISPR sequences to retain fragments of the genomes of phage that the bacteria have come into contact with in the past, which allows them to block virus replication through a form of RNA interference.

Cystic fibrosis

CFCystic fibrosis of the pancreasdisease
Riordan on the seventh chromosome. Subsequent research has found over 1,000 different mutations that cause CF. Because mutations in the CFTR gene are typically small, classical genetics techniques had been unable to accurately pinpoint the mutated gene. Using protein markers, gene-linkage studies were able to map the mutation to chromosome 7. Chromosome-walking and -jumping techniques were then used to identify and sequence the gene. In 1989, Lap-Chee Tsui led a team of researchers at the Hospital for Sick Children in Toronto that discovered the gene responsible for CF.

Gene prediction

gene findingAnnotation of genesfind genes
In empirical (similarity, homology or evidence-based) gene finding systems, the target genome is searched for sequences that are similar to extrinsic evidence in the form of the known expressed sequence tags, messenger RNA (mRNA), protein products, and homologous or orthologous sequences. Given an mRNA sequence, it is trivial to derive a unique genomic DNA sequence from which it had to have been transcribed. Given a protein sequence, a family of possible coding DNA sequences can be derived by reverse translation of the genetic code.

Prenatal testing

prenatal diagnosisprenatal screeningprenatal test
A variation of the PCR technique called multiplex ligation-dependent probe amplification (MLPA), targeting DNA, has been successively applied for diagnosing fetal aneuploidy as a chromosome- or gene-specific assay. Fetal cell DNA has been directly sequenced using shotgun sequencing technology. This DNA was obtained from the blood plasma of eighteen pregnant women. This was followed by mapping the chromosome using the quantification of fragments. This was done using advanced methods in DNA sequencing resulting in the parallel sequencing of the fetal DNA. The amount of sequence tags mapped to each chromosome was counted.

Chromosomal crossover

crossing overcrossovercrossing-over
When a high correlation between the two is found, it is likely that the appropriate gene sequence is really closer. Crossovers typically occur between homologous regions of matching chromosomes, but similarities in sequence and other factors can result in mismatched alignments. Most DNA is composed of base pair sequences repeated very large numbers of times. These repetitious segments, often referred to as satellites, are fairly homogenous among a species. During DNA replication, each strand of DNA is used as a template for the creation of new strands using a partially-conserved mechanism; proper functioning of this process results in two identical, paired chromosomes, often called sisters.


virologistvirologistsviral ecology
Assembling the 7741-base genome from scratch, starting with the virus's published RNA sequence, took about two years. In 2003 a faster method was shown to assemble the 5386-base genome of the bacteriophage Phi X 174 in 2 weeks. The giant mimivirus, in some sense an intermediate between tiny prokaryotes and ordinary viruses, was described in 2003 and sequenced in 2004. The strain of Influenza A virus subtype H1N1 that killed up to 50 million people during the Spanish flu pandemic in 1918 was reconstructed in 2005. Sequence information was pieced together from preserved tissue samples of flu victims; viable virus was then synthesized from this sequence.


Sequencing confirmed that this species originated from ''E. × robertsii, a sterile triploid hybrid between E. guttata and E. lutea,'' both of which have been introduced and naturalised in the United Kingdom. New populations of ''E. peregrina arose on the Scottish mainland and the Orkney Islands via genome duplication from local populations of E. × robertsii''. Because of a rare genetic mutation, ''E. peregrina'' is not sterile. Polyploid types are labeled according to the number of chromosome sets in the nucleus. The letter x is used to represent the number of chromosomes in a single set. Examples in animals are more common in non-vertebrates such as flatworms, leeches, and brine shrimp.

Chromosomal translocation

translocationtranslocationschromosome translocation
However, carriers of balanced reciprocal translocations have increased risks of creating gametes with unbalanced chromosome translocations, leading to Infertility, miscarriages or children with abnormalities. Genetic counseling and genetic testing are often offered to families that may carry a translocation. Most balanced translocation carriers are healthy and do not have any symptoms. It is important to distinguish between chromosomal translocations occurring in gametogenesis, due to errors in meiosis, and translocations that occur in cellular division of somatic cells, due to errors in mitosis.


horsesracehorseEquus caballus
"Ancient horse bone yields oldest DNA sequence". "Ancient horse bone yields oldest DNA sequence".


cornZea mayscorn (maize)
There are about 1000 chromosomal aberrations (e.g., translocations and inversions) and stocks with abnormal chromosome numbers (e.g., tetraploids). Genetic data describing the maize mutant stocks as well as myriad other data about maize genetics can be accessed at MaizeGDB, the Maize Genetics and Genomics Database. In 2005, the US National Science Foundation (NSF), Department of Agriculture (USDA) and the Department of Energy (DOE) formed a consortium to sequence the B73 maize genome. The resulting DNA sequence data was deposited immediately into GenBank, a public repository for genome-sequence data.


domestic catcatsFelis catus
The high level of similarity among the metabolism of mammals allows many of these feline diseases to be diagnosed using genetic tests that were originally developed for use in humans, as well as the use of cats as animal models in the study of the human diseases. Diseases affecting domestic cats include acute infections, parasitic infestations, injuries, and chronic diseases such as kidney disease, thyroid disease, and arthritis. Vaccinations are available for many infectious diseases, as are treatments to eliminate parasites such as worms and fleas. The domestic cat is a cosmopolitan species and occurs across much of the world.

Klinefelter syndrome

Klinefelter's syndrome47,XXYXXY
Symptoms are typically more severe if three or more X chromosomes are present (48,XXXY syndrome or 49,XXXXY syndrome). Klinefelter syndrome usually occurs randomly. An older mother may have a slightly increased risk of a child with KS. The condition is not typically inherited from one's parents. The underlying mechanisms involves at least one extra X chromosome in addition to a Y chromosome such that the total chromosome number is 47 or more rather than the usual 46. KS is diagnosed by the genetic test known as a karyotype. While no cure is known, a number of treatments may help. Physical therapy, speech and language therapy, counselling, and adjustments of teaching methods may be useful.

Wellcome Sanger Institute

Wellcome Trust Sanger InstituteSanger InstituteSanger Centre
The Sanger Institute was opened in 1993, three years after the inception of the Human Genome Project, and went on to make the largest single contribution to the gold standard sequence of the human genome, published in 2004. The Institute was engaged in collaborations to sequence 8 of the 23 human pairs of chromosomes (1, 6, 9, 10, 13, 20, 22, and X). Since the publishing of the human genome, research carried out at the Institute has developed beyond sequencing of organisms into various biomedical research areas, including studies into diseases such as cancer, malaria and diabetes. * COSMIC, a catalogue of somatic mutations in cancer.

Genetic privacy

genetic datagenetic information privacyprivacy of genetic information
As such, one's genetic code can be used to infer many characteristics about an individual, including many potentially sensitive subjects such as: Many types of direct-to-consumer DNA tests have been released that allow individuals to obtain genetic information from tissue obtained from the mouth, such as a cheek scraping (performed with a swab), an individual's saliva, or chewing gum. One of the most popular reasons for at-home genetic testing is to obtain information on an individual's ancestry via genealogical DNA testing and is offered by many companies such as 23andMe, AncestryDNA, Family Tree DNA, or MyHeritage.


syntenicgene ordergene order conservation
In contrast, any loci on the same chromosome are by definition syntenic, even if their recombination frequency cannot be distinguished from unlinked loci by practical experiments. Thus, in theory, all linked loci are syntenic, but not all syntenic loci are necessarily linked. Similarly, in genomics, the genetic loci on a chromosome are syntenic regardless of whether this relationship can be established by experimental methods such as DNA sequencing/assembly, genome walking, physical localization or hap-mapping.

Chromosomal inversion

inversioninversionschromosomal inversions
The most common inversion seen in humans is on chromosome 9, at inv(9)(p12q13). This inversion is generally considered to have no harmful effects, but there is some suspicion it could lead to an increased risk for miscarriage or infertility for some affected individuals. An inversion does not involve a loss of genetic information, but simply rearranges the linear gene sequence. Families that may be carriers of inversions may be offered genetic counseling and genetic testing.

Genome project

genome projectssequencedgenome annotation
Genome projects are scientific endeavours that ultimately aim to determine the complete genome sequence of an organism (be it an animal, a plant, a fungus, a bacterium, an archaean, a protist or a virus) and to annotate protein-coding genes and other important genome-encoded features. The genome sequence of an organism includes the collective DNA sequences of each chromosome in the organism. For a bacterium containing a single chromosome, a genome project will aim to map the sequence of that chromosome. For the human species, whose genome includes 22 pairs of autosomes and 2 sex chromosomes, a complete genome sequence will involve 46 separate chromosome sequences.

Cri du chat syndrome

Cri du chatCri-du-chat syndromeCri-du-chat
Genetic counseling and genetic testing may be offered to families with individuals who have cri du chat syndrome. Prenatally the deletion of the cri du chat related region in the p arm of chromosome 5 can be detected from amniotic fluid or chorionic villi samples with BACs-on-Beads technology. G-banded karyotype of a carrier is also useful. There is not a specific way to treat the condition as the brain damage caused by this condition occurs in the early stages of embryo development. Intensive treatment is rarely needed in infants and they can be treated in neonatal pathology departments. Children may be treated by speech, physical and occupational therapists.

Living DNA

After getting DNA tests results from three different companies to know if his "dad's family came from Russia", David Gewirtz says, "the results I got back from Ancestry and 23andMe were shocking and upsetting would be an understatement." While "the results from Living DNA were substantially different and led to some fascinating insights that were actually really cool, rather than painful." *


ribonucleic aciddsRNAdouble-stranded RNA
Initiation of transcription begins with the binding of the enzyme to a promoter sequence in the DNA (usually found "upstream" of a gene). The DNA double helix is unwound by the helicase activity of the enzyme. The enzyme then progresses along the template strand in the 3’ to 5’ direction, synthesizing a complementary RNA molecule with elongation occurring in the 5’ to 3’ direction. The DNA sequence also dictates where termination of RNA synthesis will occur. Primary transcript RNAs are often modified by enzymes after transcription. For example, a poly(A) tail and a 5' cap are added to eukaryotic pre-mRNA and introns are removed by the spliceosome.

DNA paternity testing

paternity testpaternity testingDNA paternity test
In testing the paternity of a male child, comparison of the Y chromosome can be used, since it is passed directly from father to son. In the US, the AABB has regulations for DNA paternity and family relationship testing; however, AABB accreditation is not necessary. DNA test results are legally admissible if the collection and the processing follows a chain of custody. Similarly in Canada, the SCC has regulations on DNA paternity and relationship testing; however, this accreditation is recommended, but not necessary.