The Identification of Tay Sachs Disease
Tay Sachs Disease is a lysosomal storage disease that was first uncovered over a century ago. Since the defective enzyme was originally identified in 1969, we are now capable of providing numerous tests and screening methods to those that may be at risk for TSD. While anyone can undergo TSD screening, it is primarily geared toward the high risk Ashkenazi Jew population. Testing was originally accomplished in the 1970s by measuring the activity of HexA in a serum or white blood cells. There are multiple methods used when testing and screening for TSD. Those methods include carrier testing, prenatal testing, enzyme assay testing and mutation analysis testing. There are also symptoms exhibited by patients
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that are key indications of TSD. One of those symptoms is the cherry red spot found in the eye of a patient. Carrier testing is designed to help detect whether an individual that is not affected by TSD is in fact carrying a copy of the gene.
Carrier testing is a popular option for couples who are looking to reproduce and are coming from at-risk populations. It is common for those who chose to undergo carrier testing to be aware of results or genetic disease in their family history. Prenatal testing is available to determine whether a fetus has inherited two, one from each parent, copies of the mutated gene that will cause TSD. Prenatal testing is generally utilized when both parents cannot be ruled out as carriers. Prenatal testing is performed via an assay of Hex A enzyme activity in the fetus’s cells. The cells are taken by chorionic villus sampling—when tissue is taken from the fetal portion of the placenta— or amniocentesis—where amniotic fluid is …show more content…
examined. We are able to test for TSD with both enzyme assay testing and mutation analysis testing. Enzyme assay testing examines the phenotype by measuring enzyme activity at the molecular level and uncovers patients with low Hex A levels. Mutation analysis looks for genetic markers by examining the genotype directly. The enzyme assay and mutation analysis testing are used together. This is due to enzyme assay testing having the ability to detect all mutations, but sometimes providing inconclusive results. Whereas mutation analysis testing provides us with definitive results for known mutations only. DNA testing became available to doctors in the 1990s. In order to be performed, saliva or buccal swabs may be used to obtain a sample in addition to blood samples. When using DNA testing in the non-Ashkenazi Jewish population, using three mutations will detect roughly 20% of carriers and using a five mutation panel will detect roughly 60% of carriers. Children with infantile type TSD will exhibit a symptom known as the cherry red spot.
The red spot is easily diagnosed with an ophthalmoscope by a physician. The red spot is found in the retinal area and appears the color red due to gangliosides residing in the retina’s ganglion cells. The cherry red spot is the only normal portion of the retina due to choroidal circulation being shown by the red in the foveal region. This is a direct result of the retinal ganglion cells being pushed aside to increase visual perception. The cherry red spot shows up in contrast the remainder of the retina. Due to the excess ganglioside storage, the retinal neurons are now distended. The below picture shows an example of the cherry red spot in a TSD
patient. There have been 78 mutations described in the Hex A gene. Of those 78 mutations, 65 of them are single base mutations, a single large deletion, 10 small deletions, and two small DNA sequence insertions. With these mutations occurring, there is a disruption to the activity of β-hexosaminidase. Of the single base substitutions, 45 of them cause a point mutation. It is 39 of the point mutations that are disease causing, three that are benign but resulting in a phenotype alteration, and three that are neutral polymorphisms. Tay Sachs Disease can also be identified by mutations in the patient’s DNA sequence via a splice site lesion. Of the recorded splice mutations relating to TSD, Over 90% of North American Ashkenazi Jews—the main demographic that is impacted by TSD—that were carriers for the disease and tested have shown a splice mutation. Those that were tested in this study displayed a splice site mutation at the boundary of exon 12 and intron 12 in the beta-hexosaminidase alpha subunit gene or a 4 base pair insertion in exon 11. The identification of the mutations that are the source of TSD is crucial in being able to provide more accurate carrier information, prenatal diagnosis, and an overall prognosis for those with the disease. It is recommended that enzymatic analysis is utilized as the primary testing method for identifying those that are carriers of TSD. DNA testing can be used to confirm and clarify the results of a TSD enzyme assay. DNA testing can also be used to provide more specific molecular information to those seeking reproductive intervention and genetic counseling.
Tay-Sachs disease is a rare hereditary disease found mainly in infants but is also found in juveniles and adults. It is caused by the abnormal metabolism of fats and is characterized by mental deterioration, blindness, and paralysis. There is no available treatment for this disease.
Tay-Sachs disease is a rare and fatal genetic disorder that destroys neurons in the brain and spinal cord. The disease appears in three forms, Juvenile Onset, Late Onset (known as LOTS), and the most common form, Infantile (also known as Classic). The differences between the three forms of the disease are related to the age at which the symptoms of the disease begin to form. Tay-Sachs results from a deficiency of the enzyme hexosaminidase A, which plays a vital role in removing a fatty substance, called GM2 gangliosides, from neurons.
Tay-Sachs disease is a rear inherited disorder that affects the nerve cells (neurons) in the brain as well as the spinal cord. This disease is an autosomal recessive genetic disorder rather than a sex-linked disorder like some think. In order to inherit Tay-Sachs disease, the gene must be inherited by both parents (Gravel, 2003). If the gene is inherited only by one parent, then the individuals will only be a carrier and has the potential of passing on this disease to their children. The odds of inheriting Tay-Sachs disease if both parents are carriers are 1-4 (25%). The chromosome responsible for the abnormality or mutation that causes Tay-Sachs disease is chromosome 15. Chromosome 15 is the one that codes for production of the enzyme hexosaminidase A (Hex-A) (Gravel, 2003).
On December 1, 2012, a patient by the name of John Dough walks into the medical assistant’s office. The patient is five foot 11 inches tall, currently he is 70 years old and weighs approximately 211 pounds. The patient has no known allergies does not smoke and has a relatively clean health record. After filling out the patient medical history forms, the patient is seen by the doctor. The patient explains to the doctor that lately he has had trouble lifting object he would not normally have trouble with, as well as walking short distances, and being very fatigued. After further examination the patient explains how he recently found a tick on his back and removed it, but now there is a red bullseye on his back. The physician suggests a blood sample be taken and sent to the laboratory. To help with weakness and fatigue he recommends the patient to get a good nights sleep and drink plenty of fluids to avoid dehydration. He also wants the patient to limit medication intake that could contribute to fatigue such as cold and allergy medicines and make sure to finish all daily exercising three to four hours before bed. The patient schedules a check up two weeks later.
Imagine if you loss control of your body but your mind stayed unaffected. You would be a prisoner in your own body, all leading up to your death sentence. That is the sad fate for the people diagnosed with Amyotrophic lateral sclerosis (ALS). “Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disorder was first described by Ran in 1850. This description was then expanded in 1873 by Charcot, who emphasized the involvement of the corticospinal tracts. In the United States, ALS is often referred to as Lou Gehrig's disease, after the famous ball player who was stricken by the disease in the midst of his career. (Yale School of Medicine, 2014)” In this paper will go through the definition, the process, the signs, the risk factors, etiology, and discus the known people that have suffered with this terminal disease.
Amyotrophic Lateral Sclerosis is a progressive neurodegenerative disease that affects nerve cells in the brain and the spinal cord. Amyotrophic Lateral Sclerosis is better known as ALS or Lou Gehrig’s disease. Amyotrophic Lateral Sclerosis was not brought to International or national attention until Famous New York Yankees baseball player, Lou Gehrig, was diagnosed with it in 1939. Jon Stone, the writer and creator of Sesame Street, was also diagnosed with Amyotrophic Lateral Sclerosis. Amyotrophic Lateral Sclerosis is very deadly and it physically handicaps a person as it progresses. There are two types of Amyotrophic Lateral Sclerosis, Sporadic and Familial. Sporadic is the most common cause in some cases and Familial is inherited, which is rare. Amyotrophic Lateral Sclerosis is one of the most aggressive muscular atrophy disorders, it has many signs and symptoms, and it can be treated but cannot be cured.
The pupil is where light can enter the eye. The iris is in control of the amount of light that actually goes through. The light reaches the lens, which alters the shape of it so the eye can focus on it. Light reaches the retina, which consists of cones and rods. Colors are saw differently based on their implied meanings, which to various psychological functions. The cones are responsible for color. The color red would have such an effect on people’s perception of others based on their production of affect, behavior and cognition. A sociocultural theorist would explain this effect by indicating that the associations with the color red are normal. When a student sees a plethora of red marks on their paper, they automatically think they failed the assignment. Biological theorist would best explain this theory by saying the color red helps them survive or reproduce. A man may be attracted to a woman more because she is wearing red. This attractiveness could cause him to find his mate and eventually reproduce. A behavioral theorist would explain this effect by saying the color red provokes pleasure and avoids pain. A person can associate red with romance and
There are many factors involved in the complexity of Sandhoff’s history, causes, and inheritance. Drs. Horst Jatzkewitz, Hartmut Pilz, and Konrad Sandhoff made the discovery of this disease in 1965. Originally these men were observing enzymes, and they found a new case of Tay-Sachs. It was then classified as an abnormal form of Tay-Sachs, but it was called Sandhoff due to the fact Konrad was given the most credit for its discovery. The determined cause of the disorder is an absence or reduced amount of the Hex A and Hex B enzyme. Without these, lipids abnormally build causing damage to cells. As a result of Sandhoff being an autosomal recessive disorder located on the 5q13 chromosome. Both parents have to be a carrier in o...
The child that I tested will be referred to as K.L. I tested her on April 14th 2016. K.L. is 2 years old, with her exact age being 2 years 9 months and 14 days. I called and asked her mother if she would mind dropping K.L. off with me for a few hours so I could perform the test, and then pick her back up after the test was complete. This test more accurate when the caregiver is not present. K.L. has a step sister and a baby brother on the way. She has always been in the daycare setting, because her grandmother is a provider. K.L. was delivered full term via planned cesarean section due to her mother’s small pelvis. There was no complications during this pregnancy. K.L. weighted 8 lbs. 4 oz. and was 20 ½ inches long at birth, now weighting in at ...
In Gattaca, the plot focuses on the ethics, the risks, and the emotional impact of genetic testing in the nearby future. The film was released in the 90s; yet in the present, the film does not give the impression of science fiction. Today, genetic testing is prevalent in many aspects of the scientific community. This paper will describe genetic testing, its purpose, diagnostic techniques that use genetic testing, relating Huntington’s disease to genetic testing, and the pros and cons of genetic testing.
second, prenatal testing, is a testing of a fetus at risk for the disease. The
Macular degeneration in general can affect many people in minor or drastic ways. People who experience this form often complain of vision loss when they are in dim light, especially when they are reading. The "dry" type is often characterized by a more gradual loss of vision compared to the "wet" type. Signs of this disease include an increase in drusen, which is an accumulation of a yellow-white substance, in the underside of the macular retina. A loss of cells can be seen in the macula. The macula is our sensitive sight region, where intricate detail can be seen. Thus, vision in this area is helpful and necessary to drive, read, focus on small details, and recognize familiar faces. The macula is located in the back of the eye known as the retina. The macula is only about 5 mm in diameter, and includes the fovea, which gives us our detailed central vision. If a person suffers from the "dry" form in one eye they will be more likely to develop it in the other eye as well.
Prenatal genetic testing has become one of the largest and most influencial advances in clinical genetics today. "Of the over 4000 genetic traits which have been distinguished to date, more than 300 are identifiable via prenatal genetic testing" (Morris, 1993). Every year, thousands of couples are subjecting their lives to the results of prenatal tests. For some, the information may be a sigh of relief, for others a tear of terror. The psychological effects following a prenatal test can be devastating, leaving the woman with a decision which will affect the rest of her life.
Prenatal genetic screening in particular is a polarizing topic of discussion, more specifically, preimplantation genetic diagnosis (PGD). PGD is one of the two techniques commonly used to genetically screen embryos in vitro; it is usually done at the eight-cell stage of division. PGD is most often performed when there is the risk that one or both parents carry disease-causing mutations. It is extensively used by high-risk individuals trying to conceive babes who will be free of particular mutations. PGD can test for over 50 genetic conditions and even allows for sex selection if there are underlying gender-associated medical conditions. When the results are satisfactory, the selected embryo is implanted into the mother’s uterus. While a controversial technique, preimplantation genetic diagnosis is one example of some of the good genetic testing can do, more benefits will be furthe...
Newborn screening is the practice in which the harmful or potentially fatal conditions that can affect the infant's health or survival are detected. This process can prevent death or health problems and protect the infant against certain diseases and medical conditions. Newborn screening started in 1960's when many states in U.S.A. established a newborn test program for phenylketonuria (PKU) by using the Guthrie method, a system for the collection and transportation of blood samples on filter paper. Many Infants showed developments while receiving treatment. This success led to the addition of tests for other metabolic diseases. Over time, tests were added for endocrine disorders and now newborn screening program include more than 50 individual conditions.