TAY SACHS AND ASHKENAZI JEWS – THE MYSTERY REVEALED:
Tay Sachs disease (TSD) is a rare genetic disorder due to some mutations on a particular gene called the HEXA gene located in the chromosome 15. The main reason as to why this disease doesn’t spread rapidly to the descendents is because it is an autosomal recessive disorder. There is only a 25% chance for the child of parents carrying copies of faulty HEXA genes to acquire the disease. However, Tay Sachs diseases is a fatal disorder characterized by deterioration of the neurons and subsequently due to the accumulation of a particular substance called GM2 gangliosides which is a type of lipid found in neurons. Due to the defective copies of the HEXA genes, the body mechanism fails to synthesize the active form of Hexosaminidase A enzyme which is responsible for the degradation of gangliosides.
There are variants of Tay Sachs Disease which are classified based on the time of onset of the disease. They are Infantile TSD, Juvenile TSD and Late Onset TSD. The infantile form of TSD is very fatal causing severe deterioration of the nerves and resulting in death of the infant by the age of 4. The juvenile form sets in between the age of 2 and 10 which is characterized by loss of cognitive and motor functions of the nerves and also results in death by the age of 15. The Late Onset TSD however is not fatal and is characterized by ataxia, psychiatric illness and neural deterioration.
The HEXA gene can be affected by over 100 different types of mutations which cause an alteration in the reading frame of the DNA resulting in a faulty enzyme. Tay Sachs disease is highly common among certain populations in the world due to continued inheritance and hybridization of a particular genetic defect described as 1278insTATC which is caused by the insertion of a base pair in exon 11 of the messenger RNA sequence. This means that an extra nucleotide has been added to the DNA sequence which transcribes and translates in the Hexosaminidase A enzyme. This totally alters the reading frame of the RNA sequence and therefore codes for different amino acids at key sites. The final product of the mutated DNA can no longer retain the functionality of the correct form of the enzyme.
This was one of the first mutations detected in a population based in Central and Eastern Europe called the Ashkenazi Jewish Population. This particular population is highly susceptible to other peculiar genetic disorders like Canavan Disease, Faconi Anemia, Cystic Fibrosis, Gauchers Disease and many more. The frequency of occurrence of TSD in Ashkenazi Jews is a startling 1 out of 30 individuals worldwide. The common form of TSD which usually affects these people is the infantile form of TSD. A major reason for the spread of this disease within the community is their rigid marital traditions and practices and also lack of awareness about the dangers of genetically inherited diseases.
However, the number of carriers of the disease is greater than the number actually affected by TSD, because the disease is not expressed in individuals possessing heterozygous alleles of HEXA gene containing one functional copy and one defective copy. So, it is very important to prevent the further spreading of the mutation among unaffected populations by efficient preventive techniques. With the advent in medical technology, it is possible to determine the genetic make-up of an individual by sampling a living tissue of the patient using techniques like PCR or ELISA to identify faulty genes or test the activity of Hexosaminidase enzymes. It is also possible to detect TSD early on in foetuses by carrying out amniocentesis or sampling of chorionic villi.
Friday, February 12, 2010
TAY SACHS DISEASE – ITS TRUE COLORS:
Tay Sachs disease, scientifically described as Hexosaminidase A deficiency is a genetic disorder resulting in severe physical and mental disabilities resulting in death. The cause for this genetic disorder is due to a mutation on the HEXA gene found in chromosome 15 which governs the production of gangliosides in the nerve cells. Tay Sachs is a rare disease because it is an autosomal recessive disease, meaning that the defective gene is not located in the sex chromosome and the disease can be inherited only if both the parents possess defective copies of the gene.
Tay Sachs disease (TSD) can be classified into three types depending on the time of onset of the symptoms and disorder. They are infantile TSD, Juvenile TSD and late onset TSD. The infantile form of the disease sets in after 6 months of the baby’s growth and goes on relentlessly till muscle atrophy and paralysis results in the death of the infant. The juvenile form of TSD is rare which sets in between the age of 2 and 10 during which they develop several complications of nervous function and results in death. The Late Onset TSD, abbreviated as LOTS sets in during the 20s and 30s. It is usually non-fatal and is characterized by swallowing and speech difficulties, unsteadiness of gait and neurological deterioration.
The inheritance of TSD adheres to Mendelian laws wherein the resulting child has 25% probability of acquiring the disease from heterozygous parents. The mutation of the HEXA gene results in the deficiency or failure of the body mechanism to synthesize an enzyme called Hexosaminidase A which catalyzes the breakdown of a special class of lipids called GM2 gangliosides. This therefore leads to accumulation of gangliosides in the neurons in the patient’s brain and interferes which its normal functioning.
There are over 100 possible mutations which can occur in the HEXA gene which encode for the Hexosaminidase A enzyme. Some of the mutations are widely expressed in specific human populations for over hundreds of years. The most notable example is the Ashkenazi Jewish population who carry a mutation 1278insTATC resulting in alteration of the messenger RNA. Apart from being directly affected by Tay Sachs disease, a majority of children born to parents with either of them possessing a defective HEXA gene can be potential carriers of the gene without being affected by the disease.
There is also another scenario wherein a child may inherit two different types of HEXA mutations which attenuate the biodegradation of gangliosides in varying degrees. Thus the afflicted individual may not have completely lost Hexosaminidase A activity. This type of a carrier is called a Compound Heterozygote.
With significant advancements in medical diagnosis and prenatal care, several measures have been introduced to prevent the spread of Tay Sachs Disease to other populations. The primary methods of preventing onset of TSD is by screening potential carriers of the defective HEXA gene and counseling them whether or not to give birth to infant. The other measure adopted is prenatal testing by which tests are conducted in the developing foetus by sampling the amniotic fluid or the chorionic villus. Biomedical and enzyme assays are also available to diagnose people affected by TSD by estimating the activity of the Hexosaminidase A enzyme.
Tay Sachs disease, scientifically described as Hexosaminidase A deficiency is a genetic disorder resulting in severe physical and mental disabilities resulting in death. The cause for this genetic disorder is due to a mutation on the HEXA gene found in chromosome 15 which governs the production of gangliosides in the nerve cells. Tay Sachs is a rare disease because it is an autosomal recessive disease, meaning that the defective gene is not located in the sex chromosome and the disease can be inherited only if both the parents possess defective copies of the gene.
Tay Sachs disease (TSD) can be classified into three types depending on the time of onset of the symptoms and disorder. They are infantile TSD, Juvenile TSD and late onset TSD. The infantile form of the disease sets in after 6 months of the baby’s growth and goes on relentlessly till muscle atrophy and paralysis results in the death of the infant. The juvenile form of TSD is rare which sets in between the age of 2 and 10 during which they develop several complications of nervous function and results in death. The Late Onset TSD, abbreviated as LOTS sets in during the 20s and 30s. It is usually non-fatal and is characterized by swallowing and speech difficulties, unsteadiness of gait and neurological deterioration.
The inheritance of TSD adheres to Mendelian laws wherein the resulting child has 25% probability of acquiring the disease from heterozygous parents. The mutation of the HEXA gene results in the deficiency or failure of the body mechanism to synthesize an enzyme called Hexosaminidase A which catalyzes the breakdown of a special class of lipids called GM2 gangliosides. This therefore leads to accumulation of gangliosides in the neurons in the patient’s brain and interferes which its normal functioning.
There are over 100 possible mutations which can occur in the HEXA gene which encode for the Hexosaminidase A enzyme. Some of the mutations are widely expressed in specific human populations for over hundreds of years. The most notable example is the Ashkenazi Jewish population who carry a mutation 1278insTATC resulting in alteration of the messenger RNA. Apart from being directly affected by Tay Sachs disease, a majority of children born to parents with either of them possessing a defective HEXA gene can be potential carriers of the gene without being affected by the disease.
There is also another scenario wherein a child may inherit two different types of HEXA mutations which attenuate the biodegradation of gangliosides in varying degrees. Thus the afflicted individual may not have completely lost Hexosaminidase A activity. This type of a carrier is called a Compound Heterozygote.
With significant advancements in medical diagnosis and prenatal care, several measures have been introduced to prevent the spread of Tay Sachs Disease to other populations. The primary methods of preventing onset of TSD is by screening potential carriers of the defective HEXA gene and counseling them whether or not to give birth to infant. The other measure adopted is prenatal testing by which tests are conducted in the developing foetus by sampling the amniotic fluid or the chorionic villus. Biomedical and enzyme assays are also available to diagnose people affected by TSD by estimating the activity of the Hexosaminidase A enzyme.
Saturday, February 6, 2010
KURUKSHETRA-THE LAND OF HOLY GITA:
Revered as one of the most ancient and sacred lands of India, Kurukshetra possesses a legendary history and is intimately associated with the miracles of Lord Krishna. It is in this land the epic Mahabharat war was fought. It is in this very same land where Lord Krishna recited the Holy Bhagavad Gita to Arjuna. Kurukshetra is also an archaeological treasure trove since the city existed even before the Harappan civilization. Currently, Kurukshetra is a prime pilgrim center in the state of Haryana in India.
It is very easy to access Kurukshetra since it is a major railhead connected to all other cities in India. It is well-linked by roads situated about 160km from Delhi, 110km from Chandigarh and 40km from Ambala. The nearest airports to Kurukshetra are located in Delhi and Chandigarh.
Since Kurukshetra is a land-locked region, it naturally experiences extremes of temperatures during summer and winter. The best time to visit Kurukshetra is between the months of September to March. The city celebrates several festivals like Holi, Baisakhi, Diwali and the city’s very own ‘Kurukshetra’ and ‘Lohri’ festivals from February till December.
Finding a cozy niche during your stay in Kurukshetra won’t be a problem since there are several private budget hotels to cater to the needs of tourists and pilgrims. You can rooms of your choice at prices of 1000-1300 INR per day.
There are several noteworthy tourist spots in Kurukshetra which attracts pilgrims from all over the country. On day one of your tour in Kurukshetra, you must visit the legendary Bhadrakali Temple located in North Thaneshwar. This temple is revered as one of the 51 Shakthi Peethas of the country and is closely associated with the Pandavas. Devotees throng this temple every weekend and during Navarathri celebrations. A peculiar feature about this temple is that devotees offer a terracotta horse as a symbol of devotion for Goddess Kali. We suggest you spend at most half a day in this temple.
After freshening yourself up with a simple yet sumptuous meal of Bajra roti with saag, you must visit the Sthaneshwar Mahadev Temple in the evening. This temple is dedicated to Lord Shiva and also holds significance with the legend of the Pandavas. The tank enclosed within the temple is said to possess curative powers and attracts many tourists. With this, you can wrap up your itinerary on day one.
On day two, start your sight-seeing venture by heading straight to the Krishna Museum. The galleries show exquisite exhibits of wood carvings, ivory works, bronze statues, stone sculptures, palm leaf writings and archaeological artifacts which are centered on the themes of Lord Krishna, the Bhagavad Gita and the Mahabharat. A visit to the museum will definitely take about 3 hours. You can wrap up your trip by visiting the Brahma Sarovar and Sannihit Sarovar and board your train or bus back home. You can spend an hour apiece relaxing along the banks of the picturesque lakes. The two lakes attract thousands of devotees during solar eclipses and Kumbh Mela respectively.
All in all, your trip to Kurukshetra can be completed briskly in two days. The cost of the tour can sum upto 2100 INR per day for an individual inclusive of accommodation charges. So what’s holding you back even now? Come visit Kurukshetra – The Land of the Holy Gita.
Revered as one of the most ancient and sacred lands of India, Kurukshetra possesses a legendary history and is intimately associated with the miracles of Lord Krishna. It is in this land the epic Mahabharat war was fought. It is in this very same land where Lord Krishna recited the Holy Bhagavad Gita to Arjuna. Kurukshetra is also an archaeological treasure trove since the city existed even before the Harappan civilization. Currently, Kurukshetra is a prime pilgrim center in the state of Haryana in India.
It is very easy to access Kurukshetra since it is a major railhead connected to all other cities in India. It is well-linked by roads situated about 160km from Delhi, 110km from Chandigarh and 40km from Ambala. The nearest airports to Kurukshetra are located in Delhi and Chandigarh.
Since Kurukshetra is a land-locked region, it naturally experiences extremes of temperatures during summer and winter. The best time to visit Kurukshetra is between the months of September to March. The city celebrates several festivals like Holi, Baisakhi, Diwali and the city’s very own ‘Kurukshetra’ and ‘Lohri’ festivals from February till December.
Finding a cozy niche during your stay in Kurukshetra won’t be a problem since there are several private budget hotels to cater to the needs of tourists and pilgrims. You can rooms of your choice at prices of 1000-1300 INR per day.
There are several noteworthy tourist spots in Kurukshetra which attracts pilgrims from all over the country. On day one of your tour in Kurukshetra, you must visit the legendary Bhadrakali Temple located in North Thaneshwar. This temple is revered as one of the 51 Shakthi Peethas of the country and is closely associated with the Pandavas. Devotees throng this temple every weekend and during Navarathri celebrations. A peculiar feature about this temple is that devotees offer a terracotta horse as a symbol of devotion for Goddess Kali. We suggest you spend at most half a day in this temple.
After freshening yourself up with a simple yet sumptuous meal of Bajra roti with saag, you must visit the Sthaneshwar Mahadev Temple in the evening. This temple is dedicated to Lord Shiva and also holds significance with the legend of the Pandavas. The tank enclosed within the temple is said to possess curative powers and attracts many tourists. With this, you can wrap up your itinerary on day one.
On day two, start your sight-seeing venture by heading straight to the Krishna Museum. The galleries show exquisite exhibits of wood carvings, ivory works, bronze statues, stone sculptures, palm leaf writings and archaeological artifacts which are centered on the themes of Lord Krishna, the Bhagavad Gita and the Mahabharat. A visit to the museum will definitely take about 3 hours. You can wrap up your trip by visiting the Brahma Sarovar and Sannihit Sarovar and board your train or bus back home. You can spend an hour apiece relaxing along the banks of the picturesque lakes. The two lakes attract thousands of devotees during solar eclipses and Kumbh Mela respectively.
All in all, your trip to Kurukshetra can be completed briskly in two days. The cost of the tour can sum upto 2100 INR per day for an individual inclusive of accommodation charges. So what’s holding you back even now? Come visit Kurukshetra – The Land of the Holy Gita.
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