Genetics and Hemophilia Genetic Testing in Populations

1. Genetics and Hemophilia Genetic Testing in Populations Axiom Therapeutics

2. Partial Overview of Genetics • Genetics – the science of genes, heredity, and variation in living organisms, specifically dealing with the molecular structure and function of genes. • Each organism has trillions of cells, which it is always replacing. Within each cell is a nucleus containing its own complete set of an individuals DNA. • DNA ( Deoxyribonucleic acid) is composed of 23 pairs of chromosomes. This equals 46 total paired chromosomes. 22 of which are autosomes. 1 pair of which are considered sex chromosomes. • These Chromosomes are composed of varying sequences of 4 different chemical base pairs: adenine, guanine, cytosine, and thymine. These base pairs code our DNA like a blueprint for a architect. Genes are segments of chromosomes which specify certain traits such as eye color, hair color and texture, facial features, and even temperament. • Example of a Gene: ACTGCTACGT. (genes are usually much longer) This gene may code for eye color. • Some characteristics need multiple genes to be expressed in the organism. • Ribosomes are the builders or architects of the proteins using the map or blueprint (DNA) handed down from your parents, and its containing genes to build you as an individual different from any other. • Optional Video: 1. http://youtu.be/eOvMNOMRRm8 • 2. http://youtu.be/5raJePXu0OQ • 3. http://youtu.be/lJzZ7p-47P8

3. The 1 pair of sex chromosomes determine hormone expression and gender. Male sex chromosomes are XY.Female sex chromosomes are XX. The Y chromosome is small and has little (but important) information. The X chromosome carries the gene which codes for the factor VIII and factor IX proteins. This is why males usually have hemophilia since they only have one X. Human Chromosomes

4. Example of a Punnett SquareX XX Y This example of paired sex chromosomes represents a carrier female reproducing with a “normal” factor leveled male. As you can see the male children have a 50/50 chance of having hemophilia and the females also have a 50/50 chance of being carriers. The males can have hemophilia because they have no second X chromosome to compensate for their other defective X chromosome.

5. Genetics of Hemophilia • Hemophilia is a lack of an important protein within the clotting cascade, either Factor VIII or Factor IX ( or the Von Will brands factor or carrier). • This protein lack is usually due to a single base pair mutation leading to a defective factor protein. This defect can vary from mild to severe depending on the mutation. However, this variance is constant within a family descent. In other words a family will almost always carry the same type of hemophilia throughout generations. • Example: say a gene or “map” for a protein reads as such: • ACTGCTAGTCATTG vs. ACTGCTAGTCATGG • This single mutation will result in ribosomes creating a factor protein which is unable to perform its duties within the coagulation cascade. This is due to chemical reactions which cause the protein to collect in a dysfunctional way. • Hemophilia can have two types: point mutation and genetic inheritance.

7. So How can we test for Hemophilia? • Human Genome Project- finished in 2003 scientists found roughly 20-25,000 genes within the human genome, mapping where each was located. Not all genes were understood or found entirely but most where named and their function is known. • Hemophiliac “Mapping”- A test can be run in which scientists locate within a hemophiliac patient’s blood where the gene mutation occurs within the individuals DNA strand. This test involves a blood draw and is usually very expensive running around 5-7,000 dollars. Once this is done these results can be used for all the carriers within a family. • Carrier testing- After the hemophiliac has been “mapped” , potential carrriers within the same family can be evaluated and their DNA evaluated for the mutation which was found in the hemophiliac patient. This test also is done through a blood draw and is usually much less expensive running around 5-600 dollars (still a lot). • “Faith Birth”- This is a term used for those potential carriers who have not been tested but proceed with labor. Precautions are taken such as prohibiting the use of suction withdrawal or episiotomy as well as having factor products and a hematologist available and on hand in case of emergency, among other precautions. This can be dangerous especially if the delivering physician is unaware of the possibility or how to treat it.

8. Hemophiliac Birth and Diagnosis • Tested Carriers- If diagnosed pre-partum as a carrier, testing will be done immediately after birth using tests such as factor level tests, and coagulation studies such as a PTT and PT. Factor may be administered if the need is seen and diagnosis is given. This process is safer with the resource of a hematologist on hand or previously consulted. • “Faith Births”- These parents will have the same tests run. It is important to note that often a first test may not be accurate due to mixing of the mothers blood and infants blood if the sample is drawn from the umbilical cord. This can result in the need for a second factor level draw and further evaluation. These tests cam take weeks to come back. • Signs and Symptoms- These include intense bleeding post-partum from the mother ( symptomatic carrier) or child. Bruising in the child or constant crying with joint swelling or un-diagnosed causes. Abnormal test results are the definitive diagnosing factor. Potential hemophiliac infants need to evaluated closely to ensure that they are not bleeding since they are unable to communicate there needs or pain other than through crying.

9. Who pays for these tests and When? • Private Insurance Companies usually will pay for genetic testing if the hemophiliac patient has already been “mapped” and a diagnosis of a bleeding disorder can be established. This should usually be done prior to pregnancy and consent from the insurance company is needed to ensure they will pay for the testing. • Bottom Line- (As we know) Insurance doesn’t want to pay unless they have to. Therefore, if you get pregnant and then want to be tested, the insurance may not pay due to fact that the medical plan for labor will not change based on the results of the tests. Insurance will usually only pay for tests which are “indicated” , or in other words will effect the ultimate outcome of treatment. • This is particularly true with government run programs such as Medicaid and Medicare who will usually not pay for either testing unless pre-approved. This process is long and difficult to achieve.

10. Hemophilia Facts • Many have speculated that if every family with a history of a bleeding disorder would refrain from having children of their own they would be able to end the line of bleeding disorders. • This is not true; Hemophilia is not only inherited but also can show up as an unseen point mutation in any health family history just due to chromosomal SNPs, which are defined as the mixing of genetic material between paired chromosomes during replication, which can sometimes result in mutation, insertion, or deletion of some genetic material. • However, it is true that Hemophilia can be reduced in the population through genetic counseling and pre-partum testing, which is usually the reason insurance companies will pay for this testing if they will at all. The process of getting these tests approved is long and frankly very difficult.

11. Types of hemophilia and carriers • Hemophilia A and B and Von Willebrands disease have previously been discussed. • However, bleeding disorders in general are defined by a factor level of 30% of normal or less. Occasionally a carrier can have levels less than this criteria and therefore be diagnosed as a symptomatic carrier or more technically a female hemophiliac. • The only other way a female can get hemophilia is through reproduction between a hemophiliac and a carrier of the gene as shown in the diagram below: • X X • X • Y

12. Other forms of bleeding disorders • Other bleeding disorders are not so clear cut and can involve many different body systems including the immune system, connective tissue, and blood components. • Other factors can sometimes be diagnosed as missing in individuals and result in less severe types of bleeding disorders. • Connective tissue deformities can also lead to bleeding disorders and are not very well know and difficult to diagnose.

13. The Process of Being Tested • Determine if a history of a bleeding disorder exists within your family history. Many people don’t even think to look at this before having children and are surprised to find they have a family history. • Determine if testing is wanted or needed. Some people prefer to leave these things to chance and deal with the results as the come, thereby saving the money needed to get tested. • Determine before getting pregnant if your insurance policy will cover genetic testing of this kind. This usually will involve establishing proof of a family history and may depend on if other members of the family have already been tested or “mapped”. It is never guaranteed that your insurance will pay for any of this testing and usually if they do it will only be a portion with an out of pocket payment needed depending on the policy. • Contact a trusted Hematologist to determine your needs and to help you through the process of getting tested. This could include your local treatment center or other clinics within your area.

14. Questions? • Thank you for your attention! • This presentation is a rough outline of the intricate details of the pathophysiology involved in genetics, reproduction, and clotting. For further information on any part of this presentation please contact Axiom Therapeutics with specific questions or clarifications. We would be happy to provide further information or help.