Advances in Gene Therapy- Sickle Cell Anemia PKU

With the advances in technology, treatments have become available for some genetic diseases. New knowledge and understanding in the genetic link to specific disorders allows science to decrease the effects of the disease, assist in the treatment, decrease the mortality rate associated with the diseases, and the potential to actually cure or prevent the diseases.

Genetics are not the only character influencing the emergence of specific diseases and disorders. The developmental stage and the environment also play a role in the expression (Gauvin, 2009). Testing can indicate the likelihood of the emergence of certain diseases, such as PKU. One test, AFP assay, or Alpha fetoprotein assay, is a maternal blood tests that reveals if the PKU recessive allele is present (Gauvin, 2009). The detection of these recessive alleles can be conducted before and after birth (Gauvin, 2009).

Women who are found to carry the PKU recessive allele are recommended to take a special diet, typically for life, but at the very least, during pregnancy (Gauvin, 2009). Failure to follow this diet may lead to miscarriage or the the increased risk of the baby having significant mental retardation (Gauvin, 2009). After the baby has been born, the testing can also occur. Babies are tested to determine if the phenylalanine is decreased and preventing the build up of toxins that lead to mental retardation (Gauvin, 2009). If detected, a special PKU diet must immediately be implemented and continued until the nervous system of the infant matures (Gauvin, 2009).

Another disease, sickle cell anemia, is finding hope in the strides of gene therapy and testing measures resulting from the research in genetic disorders and genetically linked diseases. Sickle cell anemia is more prominent in African American populations and 8% of African Americans carry the recessive gene for Sickle Cell Anemia (Gauvin, 2009). Sickle Cell Anemia results when 2 recessive alleles are expressed in combination with each other (Gauvin, 2009). With this disease, the red blood cells decrease in oxygen, resulting in the disfiguration of the cell into an elongated shape which gets caught in blood vessels leading to pain, tissue damage, chronic anemia, and possibility of death (Gauvin, 2009).

Historically, the only treatments available were blood transfusions (Gauvin, 2009). Some pharmaceuticals have been found to help with the symptoms by increasing the activity of dormant hemoglobin genes (Gauvin, 2009). The progress in gene therapy has led to hope for more effective and life saving treatments. Gene therapy involves using normal alleles to compensate for the dysfunctional alleles that lead to the disorder or disease (Gauvin, 2009). In Utero treatments that have been tried utilized bone marrow cells from the father being injected into the fetus through the mother’s abdomen (Gauvin, 2009). Safety is always a concern, even though the use of ultrasound serves as a guide (Gauvin, 2009). Another measure used is the removal of the target cells and then fusing them with the new genes, and then re-inserting them into their target place within the body (Gauvin, 2009).
Obviously medical procedures and science is moving forward quickly. The benefits of these measures include preventing diseases, curing disease, and the possibility of eventually eliminating such diseases. Genetic counseling continues to play a significant role in determining the presence of these defective alleles and determining the risks they present to the infant.

It is important to slow down, though, and consider the negative impacts of such zealous measures. Do these defective alleles have a purpose within the human development realm? Sickle cells, for example, have been found to have a positive purpose for the survival of humans. Sickle cells have been determined to also fight malaria, as their unique formation is genetically resistant to the disease that kills thousands every year (Gauvin, 2009). So, science needs to explore all of the possible outcomes of genetically altering the human cells, even if the intent is to preserve life and prevent suffering.

Valerie Poling

References:

Gauvin, P. (2009). Child Psychology: A Contemporary Viewpoint, 7th ed. In C. U. HASOP, Psychology Human Prenatal Development (pp. 3-36). McGraw-Hill Primis.


To my readers? What do you think? Are these advances, "Playing God"- are we altering human nature? Are we ridding society of unique and individual characteristics? Are we stigmatizing those that do present themself with a special characteristic such as mental retardation? Obviously no one wants their child to suffer or feel pain, but as with sickle cell, is there a higher purpose for these characteristics that we may not know?

I would love to hear your take on these advances, gene therapy, etc. I have not personally had to undergo or utilize such testing, so it has not touched me personally, but for some of you- maybe it has... Please share your thoughts and enlighten someone else to a different point of view...

Genetic testing? Gene therapy? Genetic counseling? Is it worth it?

The recent strides in genetic testing and gene therapy have opened up new possibilities and options in the prevention and detection of many genetic anomalies. The genetic exploration can occur prior to conception through genetic counseling, or after conception in the form of some high risk testing options.

Preventative genetic counseling is the least risky step in preventing genetic disorders for families attempting to have children. Through the genetic counselor, the parents are tested with the goal of determining any defective alleles present and the likelihood that a genetic disorder may be expressed due to their presence (Gauvin, 2009). Having this knowledge empowers the parents to make choices best for their family, whether to attempt conception or to utilize other means of creating a family such as donors, adoption, etc.

One such option is amniocentesis. This test allows the researcher to take amniotic fluid from the amniotic sac surrounding the fetus (Gauvin, 2009). The amniotic fluid contains the cells from the fetus and allows the analyzing of the chromosomes and genetic makeup (Gauvin, 2009). The optimal time to draw this sample is in the sixteenth week of pregnancy and carries the risk of miscarriage for the mother (Gauvin, 2009). The risk is considered to be around 1 miscarriage per 200-300 tests (Gauvin, 2009).

A second common genetic test is chorionic villi sampling. This test carries a higher risk of miscarriage than the amniocentesis, yet it is able to be performed earlier in the pregnancy at the ninth week (Gauvin, 2009). The test also allows for a risk of limb and physical deformities to arise (Gauvin, 2009). Chorionic villi sampling uses cells from the chorionic villi from the chorion to utilize as the testing sample (Gauvin, 2009). The chorion is the membrane that outermost surrounds the amniotic sac and contains identical chromosomes and genes to those of the embryos, although the chorion is not considered part of the embryo (Gauvin, 2009). This testing examines chromosome anomalies, attempts to predict chromosome disorders, and has the potential to look at the genetic markers that have been deemed indicators of many disorders (such as Alzheimer’s, Huntington’s Chorea, etc) (Gauvin, 2009).

Recently, strides have been made in the area of gene therapy in which normal alleles are inserted into the cells of the patient to attempt to compensate for the defective alleles (Gauvin, 2009). If successful, large scale, this would have obvious potential for curing and preventing many disorders and diseases that are genetically linked such as Crohn’s, Down’s syndrome, Fragile X syndrome, etc.

Controversy obviously surrounds these testing measures. One issue is that parents need to be fully informed that if an anomalies is detected, there is no guarantee that the result will be serious problems because the testing discussed does not explore or contribute to the environmental factors that are present (Gauvin, 2009). There is the fear that scientists are attempting to play God. There is also the risk of the testing procedures discussed versus the knowledge gained. Would knowing your child may be born with Down syndrome really change anything other than having the parent worry excessively? Unless the parent was considering abortion, the risks do not appear to outweigh the information obtained. This leads to another concern, would the knowledge increase the rates of abortion? As mentioned above, the environmental factors are not taken into account with these testing procedures, so it is unclear if the deformed allele will actually express. The question of what criteria warrants an abortion emerges? Could this knowledge lead to insurance companies requiring genetic testing and determining rates based on this knowledge? These are all concerns that have been expressed by society in regards to genetic testing.

A final point of concern with this testing is the stigma that then becomes attached to those with “special abilities” versus disabilities. The disabled movement has worked diligently to remove the stigmatism attached to their disabilities and to be accepted as functional members of society. Creating testing which has the potential to remove or eliminate any genetic disorder provides a negative cloud over the developmentally disabled, once again. Obviously, no parent wants their child to suffer or be treated differently; however, many people believe that everyone has a place in society regardless of their physical and mental attributes. Another concern is where the line will be drawn with the testing and gene therapy? Will science move towards allowing parents to create their own perfect child? Choosing the hair color, physical attributes, IQ? Although that may seem like Hollywood hype, history shows that some societies have already attempted this through other means.

Valerie Poling
Works Cited
Gauvin, P. (2009). Child Psychology: A Contemporary Viewpoint, 7th ed. In C. U. HASOP, Psychology Human Prenatal Development (pp. 3-36). McGraw-Hill Primis.