Applications of Genetics

Why should you care?

Establishing Identity

• Comparing DNA to rule out identity, relationships, or ancestry is becoming routine.

• This is done by looking at the entire genome and looking specifically at SNP

• SNP stands for single nucleotide polymorphisms--these are single base sites that differ among individuals but have no change on appearance or health

• Another DNA feature that is often looked for is short repeated DNA sequences.

Forensics

• Before Sept 11 2001, DNA profiling was rarely reported on by the media

• After the terrorist attacks investigators compared DNA sequences from bones and teeth collected at the scene to DNA retrieved from toothbrushes, hairbrushes, and skin samples taken from clothing

Forensics

• After that, similar efforts were used in natural disasters such as the 2004 Tsunami.

Forensics• A more typical use of genetics in forensics is to match DNA tissue left behind at a crime scene to that of a suspect

• DNA profiling can also be used to overturn convictions. Sometimes, evidence is saved in a case that contains DNA. If this evidence is analyzed after someone has been convicted, then a comparison can tell for certain if the right person has been caught

Forensics• This happened in the case of the Ford Heights Four

• These men were convicted of a gang rape and double murder and spent 18 years in prison, 2 of them on death row. The case lead to new state laws entitling death row inmates new DNA tests if there was any possibility of mistaken identity or if their conviction was from a time when DNA tests were less reliable. (Proved innocence through DNA testing, released, and awarded $36 million)

Forensics• DNA profiling can also help

adopted individuals locate blood relatives

• Databases accept DNA samples from adopted individuals and can help locate siblings

• Similarly, there are websites that allow children of sperm donors locate their biological fathers, if the men wish to be contacted

History and ancestry• DNA analysis can help flesh out

the details of history.• Consider the children of Thomas

Jefferson’s slave, Sally Hemmings.• Her children claimed to have been

fathered by TJ and rumor at the time placed Jefferson near Sally nine months before each of her 7 children were born.

• Unusual DNA was found on the Y chromosomes of known Jefferson descendents as well as the descendents of Sally Hemmings. This provides further evidence that TJ likely fathered her children!

History and ancestry

• DNA profiling has even helped to clarify relationships from Biblical times!

• Example: A small group of Jewish priests, the cohanim, all share distinctive Y chromosome DNA sequences.

History and ancestry• Researchers compared the

DNA sequences of the cohanim with that of other modern Jewish DNA, then did a mathematical analysis of how long it takes DNA to mutate, and have been able to extrapolate that the cohanim priest line originated sometime during the time of Moses.

• Jewish tradition states that the first priest was Aaron, brother of Moses. So genetics has helped to further support Biblical claims!!

History and ancestry• Even cooler: the Jewish priest

DNA also occurs in a small group of black South Africans called the Lemba

• For a long time people have thought that the Lemba could have had a Jewish origin because they have many Jewish traditions: they don’t eat pork, they circumcise their newborn sons, and they celebrate a weekly day of rest

• The DNA analysis of the Y chromosome would confirm that a Jewish origin is likely true!

Health Care• New genetic information if

changing health care. Many diseases that were not previously thought to be genetic are now thought to have some genetic component.

• The problem is that it can be hard to predict how much of a disease’s symptoms can be attributed to genetics and how much can be attributed to the environment.

Health Care• Some ways that genes can

influence your health• 1: Single gene diseases-

these are diseases that are inherited in a simple dominant recessive fashion. Put very simply, if you have the diseased gene, you get the disease! Some examples that fall into this category: Cystic fibrosis, Sickle cell anemia, Huntington's disease, hemophilia

Health Care• 2)Some genes are known

to increase the risk of getting a disease, but do not guarantee that you will get it. For example, inheriting one copy of a gene called APOE raises the risk of developing Alzheimer’s three fold. However, two copies of that gene raise the chance of getting it to fifteen fold.

Health Care• 3) Your genetic make up

influences how you will respond to medical treatment, particularly medicines. For example, some people are very slow at breaking down anti-clotting drugs, while others are extra sensitive to them and can “bleed out” at what are thought to be normal dosages.

• Identifying drug reactions based on genetics is a growing field called pharmacogenomics.