Imagine you are working as a genetic counselor. A married couple makes an appointment to speak with you. Both have a genetic disorder, but they already have one child who does not have the disorder. They would like to have more children and were told by a friend that since their first child was normal their future children would be normal as well. Explain to them the probability of future offspring being normal or having the disease (assume that this is an autosomal disease). Be sure to tell them whether the disease is brought about by a dominant or recessive allele and what fraction of their children (if any) could be carriers for the disease

Imagine you are working as a genetic counselor. A married couple makes an appointment to speak with you. Both have a genetic disorder, but they already have one child who does not have the disorder. They would like to have more children and were told by a friend that since their first child was normal their future children would be normal as well. Explain to them the probability of future offspring being normal or having the disease (assume that this is an autosomal disease). Be sure to tell them whether the disease is brought about by a dominant or recessive allele and what fraction of their children (if any) could be carriers for the disease

Name: Imagine you are working as a genetic counselor. A married couple makes
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Description: Imagine you are working as a genetic counselor. A married couple makes an appointment to speak with you. Both have a genetic disorder, but they already have one child who does not have the disorder. They would like to have more children and were told

Human Heredity: Principles and Issues (MindTap Course List)

11th Edition

ISBN:9781305251052

Author:Michael Cummings

Publisher:Michael Cummings

Chapter4: Pedigree Analysis In Human Genetics

Section: Chapter Questions

Problem 21QP: Analysis of X-Linked Dominant and Recessive Traits As a genetic counselor investigating a genetic...

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A couple was referred for genetic counseling because they wanted to know the chances of having a child with dwarfism. Both the man and the woman had achondroplasia (MIM 100800), the most common form of short-limbed dwarfism. The couple knew that this condition is inherited as an autosomal dominant trait, but they were unsure what kind of physical manifestations a child would have if it inherited both mutant alleles. They were each heterozygous for the FGFR3 (MIM 134934) allele that causes achondroplasia. Normally, the protein encoded by this gene interacts with growth factors outside the cell and receives signals that control growth and development. In achrodroplasia, a mutation alters the activity of the receptor, resulting in a characteristic form of dwarfism. Because both the normal and mutant forms of the FGFR3 protein act before birth, no treatment for achrondroplasia is available. The parents each carry one normal allele and one mutant allele of FGRF3, and they wanted information on their chances of having a homozygous child. The counsellor briefly reviewed the phenotypic features of individuals with achondroplasia. These include facial features (large head with prominent forehead; small, flat nasal bridge; and prominent jaw), very short stature, and shortening of the arms and legs. Physical examination and skeletal X-ray films are used to diagnose this condition. Final adult height is approximately 4 feet. Because achondroplasia is an autosomal dominant condition, a heterozygote has a 1-in-2, or 50%, chance of passing this trait to his or her offspring. However, about 75% of those with achondroplasia have parents of average size who do not carry the mutant allele. In these cases, achondroplasia is due to a new mutation. In the couple being counseled, each individual is heterozygous, and they are at risk for having a homozygous child with two copies of the mutated gene. Infants with homozygous achondroplasia are either stillborn or die shortly after birth. The counselor recommended prenatal diagnosis via ultrasounds at various stages of development. In addition, a DNA test is available to detect the homozygous condition prenatally. What is the chance that this couple will have a child with two copies of the dominant mutant gene? What is the chance that the child will have normal height?
A couple was referred for genetic counseling because they wanted to know the chances of having a child with dwarfism. Both the man and the woman had achondroplasia (MIM 100800), the most common form of short-limbed dwarfism. The couple knew that this condition is inherited as an autosomal dominant trait, but they were unsure what kind of physical manifestations a child would have if it inherited both mutant alleles. They were each heterozygous for the FGFR3 (MIM 134934) allele that causes achondroplasia. Normally, the protein encoded by this gene interacts with growth factors outside the cell and receives signals that control growth and development. In achrodroplasia, a mutation alters the activity of the receptor, resulting in a characteristic form of dwarfism. Because both the normal and mutant forms of the FGFR3 protein act before birth, no treatment for achrondroplasia is available. The parents each carry one normal allele and one mutant allele of FGRF3, and they wanted information on their chances of having a homozygous child. The counsellor briefly reviewed the phenotypic features of individuals with achondroplasia. These include facial features (large head with prominent forehead; small, flat nasal bridge; and prominent jaw), very short stature, and shortening of the arms and legs. Physical examination and skeletal X-ray films are used to diagnose this condition. Final adult height is approximately 4 feet. Because achondroplasia is an autosomal dominant condition, a heterozygote has a 1-in-2, or 50%, chance of passing this trait to his or her offspring. However, about 75% of those with achondroplasia have parents of average size who do not carry the mutant allele. In these cases, achondroplasia is due to a new mutation. In the couple being counseled, each individual is heterozygous, and they are at risk for having a homozygous child with two copies of the mutated gene. Infants with homozygous achondroplasia are either stillborn or die shortly after birth. The counselor recommended prenatal diagnosis via ultrasounds at various stages of development. In addition, a DNA test is available to detect the homozygous condition prenatally. Should the parents be concerned about the heterozygous condition as well as the homozygous mutant condition?
As a physician, you deliver a baby with protruding heels and clenched fists with the second and fifth fingers over-lapping the third and fourth fingers. a. What genetic disorder do you suspect the baby has? b. How do you confirm your suspicion?
Mike was referred for genetic counseling because he was concerned about his extensive family history of colon cancer. That family history was highly suggestive of hereditary nonpolyposis colon cancer (HNPCC). This predisposition is inherited as an autosomal dominant trait, and those who carry the mutant allele have a 75% chance of developing colon cancer by age 65. Mike was counseled about the inheritance of this condition, the associated cancers, and the possibility of genetic testing (on an affected family member). Mikes aunt elected to be tested for one of the genes that may be altered in this condition and discovered that she did have an altered MSH2 gene. Other family members are in the process of being tested for this mutation. Once a family member is tested for the mutant allele, is it hard for other family members to remain unaware of their own fate, even if they did not want this information? How could family dynamics help or hurt this situation?
Mike was referred for genetic counseling because he was concerned about his extensive family history of colon cancer. That family history was highly suggestive of hereditary nonpolyposis colon cancer (HNPCC). This predisposition is inherited as an autosomal dominant trait, and those who carry the mutant allele have a 75% chance of developing colon cancer by age 65. Mike was counseled about the inheritance of this condition, the associated cancers, and the possibility of genetic testing (on an affected family member). Mikes aunt elected to be tested for one of the genes that may be altered in this condition and discovered that she did have an altered MSH2 gene. Other family members are in the process of being tested for this mutation. Is colon cancer treatable? What are the common treatments, and how effective are they?
Mike was referred for genetic counseling because he was concerned about his extensive family history of colon cancer. That family history was highly suggestive of hereditary nonpolyposis colon cancer (HNPCC). This predisposition is inherited as an autosomal dominant trait, and those who carry the mutant allele have a 75% chance of developing colon cancer by age 65. Mike was counseled about the inheritance of this condition, the associated cancers, and the possibility of genetic testing (on an affected family member). Mikes aunt elected to be tested for one of the genes that may be altered in this condition and discovered that she did have an altered MSH2 gene. Other family members are in the process of being tested for this mutation. Seventy-five percent of people who carry the mutant allele will get colon cancer by age 65. This is an example of incomplete penetrance. What could cause this?
Imagine you are working as a genetic counselor. A married couple makes an appointment to speak with you. Both have a genetic disorder, but they already have one child who does not have the disorder. They would like to have more children and were told by a friend that since their first child was normal their future children would be normal as well. Explain to them the probability of future offspring being normal or having the disease (assume that this is an autosomal disease). Be sure to tell them whether the disease is brought about by a dominant or recessive allele and what fraction of their children (if any) could be carriers for the disease.
A young lady requested pre-marital genetic counselling because her sister had died in infancy of gangliosidosis, an autosomal recessive disease. What is the risk that this young lady has similarly affected offspring? What advice should be given?
A woman knows that her mother is a carrier of Kartagener’s syndrome (an autosomal recessive disorder). The woman does not know if either she or her husband are carriers. The couple wants to have a child, but is worried about whether or not they could have a child with Kartagener’s syndrome. Should the couple seek the advice of a genetic counselor? In other words, is there a chance they could have an affected child? If there is a chance, please make sure your answer includes the specific parental genotypes necessary to make this possible.
Imagine that you are a genetic counselor, and a couple planning to start a family comes to you for information. Charles wasmarried once before, and he and his first wife had a child withcystic fibrosis. The brother of his current wife, Elaine, died ofcystic fibrosis. What is the probability that Charles and Elainewill have a baby with cystic fibrosis? (Neither Charles, Elaine,nor their parents have cystic fibrosis.)
Geneticists are concerned about three different genetic conditions present within their family. Achondroplasia is an autosomal dominant genetic disorder that results in short-limbed dwarfism. (A = achondroplasia allele; a = average height allele). Red-Green Color blindness is an X-linked recessive genetic disorder (Xc = color blindness allele; XC = normal color vision allele). The 7-year-old son has an autosomal recessive form of deafness. (h = deafness allele; H = normal hearing allele.) All three family members were karyotyped, and additional genetic testing was performed to determine the chromosomal location of the genes being studied. The figures below show the karyotypes of the mother and father with respect to the chromosomes containing the three genes mentioned above. Question: The couple’s 7-year-old son has all three of these genetic conditions (achondroplasia, color blindness and deafness). Taking into consideration the genotypes of his parents, what is the complete…
You met with two parents whose first child has sickle cell anemia. (The parents show no signs of the disease themselves). The mother comes to you in the third month of her second pregnancy, and wants to know if this child will also inherit the disease. As a genetics counselor, you are ready to evaluate this couple’s case by doing the following:1. Determine what the genotype of each parent is. Is this disease autosomal or sex-linked? Dominant or recessive?