Aa
Genotype?
can anybody help me to know what is Genotype?
We did it again Bill....told ya!
Sam,
Correction: website should read hcvadvocate.org
Sam,
Correction: website should read hcvadvocate.org
Sam, here is some info on genotype. I will list several good websites which will give you much information regarding hepc and treatments.
janis7hepc.com
hcvadovate.orog
_________________________________________________________________________
Genotype
All About Genotype
Genotype-related Response Rate to Interferon Treatment:
Genotype 1
(particularly 1b), prevalent in the US & Canada, is considered to be quite resistant to treatment using Interferon based formulas.
Genotype 2
(or 2a and 2b), in comparison to type 1 appears to have a much higher rate of response to treatment using Interferon-based formulas.
Genotype 3
also appears to have a higher response rate than type 1.
Genotype 4
appears to be less responsive to treatment using Interferon than type 2 & 3.
--------------------------------------------------------------------------------
What does the term genotype mean?
Genotype refers to the genetic make-up of an organism or a virus. There are at least six distinct HCV genotypes identified. Genotype 1 is the most common genotype seen in the U.S. HCV is an RNA virus related to the flavivirus family. RNA viruses are genetically less stable than DNA viruses and are prone to mutate during replication. It’s a common misconception that hepatitis C is just one virus, but in reality (as a result of mutation over hundreds of years), it’s a group of very closely related strains. They are similar enough to be called HCV, but based on genetic differences, they can be classified into distinct groups called genotypes.
What is a Genotype? (How many different types are there?)
Our special thanks to Sharon Nicholson
One way to understand the terminology of HCV like ‘genotypes’ and ‘subtypes’ is to compare them to things that we can more readily relate to.
Example:
Imagine that Viruses are like canines. Dogs have evolved into different types, just like the thousands of different viruses. Imagine that all terriers are the hepatitis C viruses, Now each type of terrier is representing different genotypes of Hepatitis C.
All terriers are still dogs, but the Australian Terrier is different from the Fox Terrier, just as the Bull Terrier is different from the Border Terrier.
You could take one major terrier type and imagine these as being one of HCV’s main types (genotypes). Like the Schnauzer. There are different types of Schnauzers like the Miniature and the Standard. That represents the different subgroups within each genotype.
Now scientists predict that people who have hepatitis C, have billions of actual viruses circulating within their body. Although there may be one or two predominant sub-types, the infection as a whole is not a single entity and is composed of many different quasispecies.
It’s believed that of the estimated 160,000 Australians with HCV, approx. 35% have subtype ‘1a’, 15% have ‘1b’, 7% have ‘2’, 35% have ‘3’ (mostly being 3a). The remaining people would have other genotypes.
Genotype and Treatment
Current scientific belief is that factors such as which genotype patients carry, their duration of a HCV infection, their HCV viral load, their age, and grade of liver inflammation or stage of fibrosis may play an important role in determining response to interferon treatment. Recent studies have suggested that a person’s HCV subtype is the key-factor that influences their possible response to interferon, or interferon-ribavirin combination treatment.
It is very important to find out which genotype you carry.
Most of us learn about Hepatitis C as one disease, however in actuality it's really several different strains of a virus. They are all similar enough to be called hepatitis C virus, yet different enough to be classified into subgroups.
HCV GENOTYPES are broken down into sub-types, some of which include: 1a, 1b, 1c 2a, 2b, 2c 3a, 3b 4a, 4b, 4c, 4d, 4e 5a 6a 7a, 7b 8a, 8b 9a 10a 11a
Genotype Geography Patterns:
It is believed that the hepatitis C virus has evolved over a period of several thousand years. This would explain the current general global patterns of genotypes and subtypes:
1a - mostly found in North & South America; also common in Australia
1b - mostly found in Europe and Asia.
2a - is the most common genotype 2 in Japan and China.
2b - is the most common genotype 2 in the US and Northern Europe.
2c - the most common genotype 2 in Western and Southern Europe.
3a - highly prevalent here in Australia (40% of cases) and South Asia.
4a - highly prevalent in Egypt
4c - highly prevalent in Central Africa
5a - highly prevalent only in South Africa
6a - restricted to Hong Kong, Macau and Vietnam
7a and 7b - common in Thailand
8a, 8b & 9a - prevalent in Vietnam
10a & 11a - found in Indonesia
Is it necessary to do genotyping when managing a person with chronic hepatitis C?
No. Although persons with genotype 1 respond less often to treatment, genotype should not be a deciding factor on whether or not to treat. With newer therapies, however, treatment regimens might differ on the basis of genotypes.
Why do most persons remain infected?
Persons infected with HCV mount an antibody response to parts of the virus, but changes in the virus during infection result in changes that are not recognized by preexisting antibodies. This appears to be how the virus establishes and maintains long-lasting infection.
Can persons become infected with different genotypes?
Yes. Because of the ineffective immune response described above, prior infection does not protect against reinfection with the same or different genotypes of the virus. For the same reason, there is no effective pre- or postexposure prophylaxis (i.e, immune globulin) available.
What is a Quasispecies?
As the virus continues to replicate in each person, there is the potential for quasispecies to form. Quasispecies are very closely related mutations of the original virus they were infected with. Over time the diversity of quasispecies increases and may affect response to treatment.
Do Genotypes Play a role in Disease Progression?
This is still a controversial area. Many studies have shown genotype 1, especially type 1b to be associated with more advanced liver disease, however these patients are generally older and have a longer duration of infection. Poynard et al assessed factors associated with fibrosis progression in a large study involving 2,235 patients. No link was found between genotype and fibrosis progression.
What about Genotypes and Treatment?
Research has shown people with genotypes 2 or 3 have a higher sustained response rate (60-70%) to combination therapy than genotype 1 (20-30%). However other factors such as stage of fibrosis or cirrhosis, viral load, age, gender, duration of disease and excessive alcohol consumption also influence response to therapy.
Furthermore the duration of treatment is also influenced by genotype. Previously untreated patients with genotype 1 double their chance of a sustained response when treated for 12 months instead of 6 months. Conversely 12 months treatment for patients with genotypes 2 or 3 does not improve response rates over 6 months treatment.
janis7hepc.com
hcvadovate.orog
_________________________________________________________________________
Genotype
All About Genotype
Genotype-related Response Rate to Interferon Treatment:
Genotype 1
(particularly 1b), prevalent in the US & Canada, is considered to be quite resistant to treatment using Interferon based formulas.
Genotype 2
(or 2a and 2b), in comparison to type 1 appears to have a much higher rate of response to treatment using Interferon-based formulas.
Genotype 3
also appears to have a higher response rate than type 1.
Genotype 4
appears to be less responsive to treatment using Interferon than type 2 & 3.
--------------------------------------------------------------------------------
What does the term genotype mean?
Genotype refers to the genetic make-up of an organism or a virus. There are at least six distinct HCV genotypes identified. Genotype 1 is the most common genotype seen in the U.S. HCV is an RNA virus related to the flavivirus family. RNA viruses are genetically less stable than DNA viruses and are prone to mutate during replication. It’s a common misconception that hepatitis C is just one virus, but in reality (as a result of mutation over hundreds of years), it’s a group of very closely related strains. They are similar enough to be called HCV, but based on genetic differences, they can be classified into distinct groups called genotypes.
What is a Genotype? (How many different types are there?)
Our special thanks to Sharon Nicholson
One way to understand the terminology of HCV like ‘genotypes’ and ‘subtypes’ is to compare them to things that we can more readily relate to.
Example:
Imagine that Viruses are like canines. Dogs have evolved into different types, just like the thousands of different viruses. Imagine that all terriers are the hepatitis C viruses, Now each type of terrier is representing different genotypes of Hepatitis C.
All terriers are still dogs, but the Australian Terrier is different from the Fox Terrier, just as the Bull Terrier is different from the Border Terrier.
You could take one major terrier type and imagine these as being one of HCV’s main types (genotypes). Like the Schnauzer. There are different types of Schnauzers like the Miniature and the Standard. That represents the different subgroups within each genotype.
Now scientists predict that people who have hepatitis C, have billions of actual viruses circulating within their body. Although there may be one or two predominant sub-types, the infection as a whole is not a single entity and is composed of many different quasispecies.
It’s believed that of the estimated 160,000 Australians with HCV, approx. 35% have subtype ‘1a’, 15% have ‘1b’, 7% have ‘2’, 35% have ‘3’ (mostly being 3a). The remaining people would have other genotypes.
Genotype and Treatment
Current scientific belief is that factors such as which genotype patients carry, their duration of a HCV infection, their HCV viral load, their age, and grade of liver inflammation or stage of fibrosis may play an important role in determining response to interferon treatment. Recent studies have suggested that a person’s HCV subtype is the key-factor that influences their possible response to interferon, or interferon-ribavirin combination treatment.
It is very important to find out which genotype you carry.
Most of us learn about Hepatitis C as one disease, however in actuality it's really several different strains of a virus. They are all similar enough to be called hepatitis C virus, yet different enough to be classified into subgroups.
HCV GENOTYPES are broken down into sub-types, some of which include: 1a, 1b, 1c 2a, 2b, 2c 3a, 3b 4a, 4b, 4c, 4d, 4e 5a 6a 7a, 7b 8a, 8b 9a 10a 11a
Genotype Geography Patterns:
It is believed that the hepatitis C virus has evolved over a period of several thousand years. This would explain the current general global patterns of genotypes and subtypes:
1a - mostly found in North & South America; also common in Australia
1b - mostly found in Europe and Asia.
2a - is the most common genotype 2 in Japan and China.
2b - is the most common genotype 2 in the US and Northern Europe.
2c - the most common genotype 2 in Western and Southern Europe.
3a - highly prevalent here in Australia (40% of cases) and South Asia.
4a - highly prevalent in Egypt
4c - highly prevalent in Central Africa
5a - highly prevalent only in South Africa
6a - restricted to Hong Kong, Macau and Vietnam
7a and 7b - common in Thailand
8a, 8b & 9a - prevalent in Vietnam
10a & 11a - found in Indonesia
Is it necessary to do genotyping when managing a person with chronic hepatitis C?
No. Although persons with genotype 1 respond less often to treatment, genotype should not be a deciding factor on whether or not to treat. With newer therapies, however, treatment regimens might differ on the basis of genotypes.
Why do most persons remain infected?
Persons infected with HCV mount an antibody response to parts of the virus, but changes in the virus during infection result in changes that are not recognized by preexisting antibodies. This appears to be how the virus establishes and maintains long-lasting infection.
Can persons become infected with different genotypes?
Yes. Because of the ineffective immune response described above, prior infection does not protect against reinfection with the same or different genotypes of the virus. For the same reason, there is no effective pre- or postexposure prophylaxis (i.e, immune globulin) available.
What is a Quasispecies?
As the virus continues to replicate in each person, there is the potential for quasispecies to form. Quasispecies are very closely related mutations of the original virus they were infected with. Over time the diversity of quasispecies increases and may affect response to treatment.
Do Genotypes Play a role in Disease Progression?
This is still a controversial area. Many studies have shown genotype 1, especially type 1b to be associated with more advanced liver disease, however these patients are generally older and have a longer duration of infection. Poynard et al assessed factors associated with fibrosis progression in a large study involving 2,235 patients. No link was found between genotype and fibrosis progression.
What about Genotypes and Treatment?
Research has shown people with genotypes 2 or 3 have a higher sustained response rate (60-70%) to combination therapy than genotype 1 (20-30%). However other factors such as stage of fibrosis or cirrhosis, viral load, age, gender, duration of disease and excessive alcohol consumption also influence response to therapy.
Furthermore the duration of treatment is also influenced by genotype. Previously untreated patients with genotype 1 double their chance of a sustained response when treated for 12 months instead of 6 months. Conversely 12 months treatment for patients with genotypes 2 or 3 does not improve response rates over 6 months treatment.
Hello, Samnomi, this is from:
http://janis7hepc.com/Genotypes.htm
“Example:
Imagine that Viruses are like canines. Dogs have evolved into different types, just like the thousands of different viruses. Imagine that all terriers are the hepatitis C viruses, Now each type of terrier is representing different genotypes of Hepatitis C.
All terriers are still dogs, but the Australian Terrier is different from the Fox Terrier, just as the Bull Terrier is different from the Border Terrier.
You could take one major terrier type and imagine these as being one of HCV’s main types (genotypes). Like the Schnauzer. There are different types of Schnauzers like the Miniature and the Standard. That represents the different subgroups within each genotype.”
http://janis7hepc.com/Genotypes.htm
“Example:
Imagine that Viruses are like canines. Dogs have evolved into different types, just like the thousands of different viruses. Imagine that all terriers are the hepatitis C viruses, Now each type of terrier is representing different genotypes of Hepatitis C.
All terriers are still dogs, but the Australian Terrier is different from the Fox Terrier, just as the Bull Terrier is different from the Border Terrier.
You could take one major terrier type and imagine these as being one of HCV’s main types (genotypes). Like the Schnauzer. There are different types of Schnauzers like the Miniature and the Standard. That represents the different subgroups within each genotype.”
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