[Elena Zueva] If parents are carriers of mutations in different genes, will a child who has a genotype with two faulty genes (for example, connexin and another) be hearing-impaired?
We must be aware that every gene has a duplicate – one variant from the mother, and one from the father. So if we talk about the connexin 26 gene – indeed, if both variants of it have mutations, this will lead to hearing loss. In other cases, when we have flaws in different genes – for example, one of the parents may have flaws in both variants of the connexin 26 gene, and the other could be hearing-impaired because of problems in another gene (but the connexin gene is wholesome). This couple will produce normally hearing children, because different genes are accountable for different proteins.

[Екатерина] A child was diagnosed with bilateral chronic profound sensorineural hearing loss, prelingual, sporadic, genetic (autosome recessive OMIM 220290). Molecular screening revealed the proband as heterozygote carrier of the mutation 35delG in the connexin 26 gene (GJB2).
We would like to ask for advice.
What is the maximum we can do to now have a healthy child?
Maybe a certain hiatus is needed between pregnancies, or the children should be of different gender? Slide 26 of your presentation made me think of this.

Carriership of a mutation means the presence of one recessive mutation, which does not lead to hearing loss. HL is the result of a combination of two recessive mutations. Therefore, if search of only one mutation was conducted, the analysis is incomplete. The whole gene must be screened and the second mutation located.
The connexin 26 gene is located on a regular chromosome and is not linked with gender (the sexual X and Y chromosomes). Therefore, boys and girls, second and firstborn children are equally susceptible. Both older and younger children can be healthy, in the current marriage or in another. For two carriers of the mutation, the risk for every pregnancy is 25%. The sperm and egg cells contain only one variant of the gene, and so we cannot predict which of them will combine. There is a 50% likelihood of a carrier passing on his modified gene to a healthy child.

[Роман г.Владикавказ] Is there a point in having a genetic analysis at the maternity ward if we have audiological screening anyway? Is this really necessary?
Experience indicates it would be of some benefit if a genetic analysis could be used to support audiological screening. Around 10-12% of children with a modified connexin 26 gene pass the OAE test, so we miss these 10-12%. If we had access to a report on a pathological genotype, the child would be given complete audiological assessment immediately, instead of repeat OAE registrations, which is what we do now.

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[Elena Zueva] If parents are carriers of mutations in different genes, will a child who has a genotype with two faulty genes (for example, connexin and another) be hearing-impaired?
We must be aware that every gene has a duplicate – one variant from the mother, and one from the father. So if we talk about the connexin 26 gene – indeed, if both variants of it have mutations, this will lead to hearing loss. In other cases, when we have flaws in different genes – for example, one of the parents may have flaws in both variants of the connexin 26 gene, and the other could be hearing-impaired because of problems in another gene (but the connexin gene is wholesome). This couple will produce normally hearing children, because different genes are accountable for different proteins.

[Екатерина] A child was diagnosed with bilateral chronic profound sensorineural hearing loss, prelingual, sporadic, genetic (autosome recessive OMIM 220290). Molecular screening revealed the proband as heterozygote carrier of the mutation 35delG in the connexin 26 gene (GJB2).
We would like to ask for advice.
What is the maximum we can do to now have a healthy child?
Maybe a certain hiatus is needed between pregnancies, or the children should be of different gender? Slide 26 of your presentation made me think of this.

Carriership of a mutation means the presence of one recessive mutation, which does not lead to hearing loss. HL is the result of a combination of two recessive mutations. Therefore, if search of only one mutation was conducted, the analysis is incomplete. The whole gene must be screened and the second mutation located.
The connexin 26 gene is located on a regular chromosome and is not linked with gender (the sexual X and Y chromosomes). Therefore, boys and girls, second and firstborn children are equally susceptible. Both older and younger children can be healthy, in the current marriage or in another. For two carriers of the mutation, the risk for every pregnancy is 25%. The sperm and egg cells contain only one variant of the gene, and so we cannot predict which of them will combine. There is a 50% likelihood of a carrier passing on his modified gene to a healthy child.

[Роман г.Владикавказ] Is there a point in having a genetic analysis at the maternity ward if we have audiological screening anyway? Is this really necessary?
Experience indicates it would be of some benefit if a genetic analysis could be used to support audiological screening. Around 10-12% of children with a modified connexin 26 gene pass the OAE test, so we miss these 10-12%. If we had access to a report on a pathological genotype, the child would be given complete audiological assessment immediately, instead of repeat OAE registrations, which is what we do now.

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[Elena Zueva] If parents are carriers of mutations in different genes, will a child who has a genotype with two faulty genes (for example, connexin and another) be hearing-impaired?
We must be aware that every gene has a duplicate – one variant from the mother, and one from the father. So if we talk about the connexin 26 gene – indeed, if both variants of it have mutations, this will lead to hearing loss. In other cases, when we have flaws in different genes – for example, one of the parents may have flaws in both variants of the connexin 26 gene, and the other could be hearing-impaired because of problems in another gene (but the connexin gene is wholesome). This couple will produce normally hearing children, because different genes are accountable for different proteins.

[Екатерина] A child was diagnosed with bilateral chronic profound sensorineural hearing loss, prelingual, sporadic, genetic (autosome recessive OMIM 220290). Molecular screening revealed the proband as heterozygote carrier of the mutation 35delG in the connexin 26 gene (GJB2).
We would like to ask for advice.
What is the maximum we can do to now have a healthy child?
Maybe a certain hiatus is needed between pregnancies, or the children should be of different gender? Slide 26 of your presentation made me think of this.

Carriership of a mutation means the presence of one recessive mutation, which does not lead to hearing loss. HL is the result of a combination of two recessive mutations. Therefore, if search of only one mutation was conducted, the analysis is incomplete. The whole gene must be screened and the second mutation located.
The connexin 26 gene is located on a regular chromosome and is not linked with gender (the sexual X and Y chromosomes). Therefore, boys and girls, second and firstborn children are equally susceptible. Both older and younger children can be healthy, in the current marriage or in another. For two carriers of the mutation, the risk for every pregnancy is 25%. The sperm and egg cells contain only one variant of the gene, and so we cannot predict which of them will combine. There is a 50% likelihood of a carrier passing on his modified gene to a healthy child.

[Роман г.Владикавказ] Is there a point in having a genetic analysis at the maternity ward if we have audiological screening anyway? Is this really necessary?
Experience indicates it would be of some benefit if a genetic analysis could be used to support audiological screening. Around 10-12% of children with a modified connexin 26 gene pass the OAE test, so we miss these 10-12%. If we had access to a report on a pathological genotype, the child would be given complete audiological assessment immediately, instead of repeat OAE registrations, which is what we do now.

Print Friendly, PDF & Email

[Elena Zueva] If parents are carriers of mutations in different genes, will a child who has a genotype with two faulty genes (for example, connexin and another) be hearing-impaired?
We must be aware that every gene has a duplicate – one variant from the mother, and one from the father. So if we talk about the connexin 26 gene – indeed, if both variants of it have mutations, this will lead to hearing loss. In other cases, when we have flaws in different genes – for example, one of the parents may have flaws in both variants of the connexin 26 gene, and the other could be hearing-impaired because of problems in another gene (but the connexin gene is wholesome). This couple will produce normally hearing children, because different genes are accountable for different proteins.

[Екатерина] A child was diagnosed with bilateral chronic profound sensorineural hearing loss, prelingual, sporadic, genetic (autosome recessive OMIM 220290). Molecular screening revealed the proband as heterozygote carrier of the mutation 35delG in the connexin 26 gene (GJB2).
We would like to ask for advice.
What is the maximum we can do to now have a healthy child?
Maybe a certain hiatus is needed between pregnancies, or the children should be of different gender? Slide 26 of your presentation made me think of this.

Carriership of a mutation means the presence of one recessive mutation, which does not lead to hearing loss. HL is the result of a combination of two recessive mutations. Therefore, if search of only one mutation was conducted, the analysis is incomplete. The whole gene must be screened and the second mutation located.
The connexin 26 gene is located on a regular chromosome and is not linked with gender (the sexual X and Y chromosomes). Therefore, boys and girls, second and firstborn children are equally susceptible. Both older and younger children can be healthy, in the current marriage or in another. For two carriers of the mutation, the risk for every pregnancy is 25%. The sperm and egg cells contain only one variant of the gene, and so we cannot predict which of them will combine. There is a 50% likelihood of a carrier passing on his modified gene to a healthy child.

[Роман г.Владикавказ] Is there a point in having a genetic analysis at the maternity ward if we have audiological screening anyway? Is this really necessary?
Experience indicates it would be of some benefit if a genetic analysis could be used to support audiological screening. Around 10-12% of children with a modified connexin 26 gene pass the OAE test, so we miss these 10-12%. If we had access to a report on a pathological genotype, the child would be given complete audiological assessment immediately, instead of repeat OAE registrations, which is what we do now.

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Tatyana Markova answers the questions of experts and parents in the webinar on Genetics, 31.03.2013

[Elena Zueva] If parents are carriers of mutations in different genes, will a child who has a genotype with two faulty genes (for example, connexin and another) be hearing-impaired?
We must be aware that every gene has a duplicate – one variant from the mother, and one from the father. So if we talk about the connexin 26 gene – indeed, if both variants of it have mutations, this will lead to hearing loss. In other cases, when we have flaws in different genes – for example, one of the parents may have flaws in both variants of the connexin 26 gene, and the other could be hearing-impaired because of problems in another gene (but the connexin gene is wholesome). This couple will produce normally hearing children, because different genes are accountable for different proteins.

[Екатерина] A child was diagnosed with bilateral chronic profound sensorineural hearing loss, prelingual, sporadic, genetic (autosome recessive OMIM 220290). Molecular screening revealed the proband as heterozygote carrier of the mutation 35delG in the connexin 26 gene (GJB2).
We would like to ask for advice.
What is the maximum we can do to now have a healthy child?
Maybe a certain hiatus is needed between pregnancies, or the children should be of different gender? Slide 26 of your presentation made me think of this.

Carriership of a mutation means the presence of one recessive mutation, which does not lead to hearing loss. HL is the result of a combination of two recessive mutations. Therefore, if search of only one mutation was conducted, the analysis is incomplete. The whole gene must be screened and the second mutation located.
The connexin 26 gene is located on a regular chromosome and is not linked with gender (the sexual X and Y chromosomes). Therefore, boys and girls, second and firstborn children are equally susceptible. Both older and younger children can be healthy, in the current marriage or in another. For two carriers of the mutation, the risk for every pregnancy is 25%. The sperm and egg cells contain only one variant of the gene, and so we cannot predict which of them will combine. There is a 50% likelihood of a carrier passing on his modified gene to a healthy child.

[Роман г.Владикавказ] Is there a point in having a genetic analysis at the maternity ward if we have audiological screening anyway? Is this really necessary?
Experience indicates it would be of some benefit if a genetic analysis could be used to support audiological screening. Around 10-12% of children with a modified connexin 26 gene pass the OAE test, so we miss these 10-12%. If we had access to a report on a pathological genotype, the child would be given complete audiological assessment immediately, instead of repeat OAE registrations, which is what we do now.

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