Step 3: Ex: * make sure to put the big letter first! A a a A a a a a a > How to write a genotype/phenotype ratio: Cheat for genotype: Cheat for phenotype: * Practice Problems: > In the space below, use the draw feature to follow along with the practice problems.

Use the following information to respond to the three questions posed below: (1) The proband (affected individual who led to the construction of the pedigree) exhibits the trait. (2) Neither her husband nor her only sibling, an older brother, exhibits the trait. (3) The proband has five children by her current husband. The oldest is a boy, followed by a girl, then another boy, and then identical twin girls. Only the second oldest fails to exhibit the trait. (4) Both parents of the proband show the trait. a. Construct a pedigree of the trait in this family. b. Determine how the trait is inherited (go step by step to examine each possible pattern of inheritance). c. Can you deduce the genotype of the probands husband for this trait?

The ABO blood system has been used to settle cases of disputed paternity. Suppose, as a geneticist, you must testify during a case in which the mother has type A blood, the child has type O blood, and the alleged father has type B blood. How would you respond to the following statements? a. Mans attorney: The mother has type A blood, so the childs type O blood must have come from the father. Because my client has type B blood, he could not be the father. b. Mothers attorney: Further tests prove this man is heterozygous, so he must be the father.

A couple has had a child born with neurofibromatosis. They come to your genetic counseling office for help. After taking an extensive family history, you determine that there is no history of this disease on either side of the family. The couple wants to have another child and wants to be advised about the risks of that child having neurofibromatosis. What advice do you give them?

Pedigree Analysis Is a Basic Method in Human Genetics Pedigree analysis permits all of the following except: a. an orderly presentation of family information b. the determination of whether a trait is genetic c. the determination of whether a trait is dominant or recessive d. an understanding of which gene is involved in a heritable disorder e. the determination of whether a trait is sex-linked or autosomal

Pedigree Analysis Is a Basic Method in Human Genetic: What are the reasons that pedigree charts are used?

A couple who wishes to have children visits you, a genetic counselor. There is a history of a deleterious recessive trait in males in the womans family but not in the mans family. The couple is convinced that because his family shows no history of this genetic disease, they are not at risk of having affected children. What steps would you take to assess this situation and educate the couple?

Jan is concerned about using ART. She wants to be the genetic mother and have Darryl be the genetic father of any children they have. What methods of ART would you recommend to this couple? Jan, a 32-year-old woman, and her husband, Darryl, have been married for 7 years. They have attempted to have a baby on several occasions. Five years ago, they had a first-trimester miscarriage, followed by an ectopic pregnancy later the same year. Jan continued to see her OB/GYN physician for infertility problems but was very dissatisfied with the response. After four miscarriages, she went to see a fertility specialist, who diagnosed her with severe endometriosis and polycystic ovarian disease (detected by hormone studies). The infertility physician explained that these two conditions were hampering her ability to become pregnant and thus making her infertile. She referred Jan to a genetic counselor. At the appointment, the counselor explained to Jan that one form of endometriosis (MIM 131200) can be a genetic disorder, and that polycystic ovarian disease can also be a genetic disorder (MIM 184700) and is one of the most common reproductive disorders among women. The counselor recommended that a detailed family history of both Jan and Darryl would help establish whether Jans problems have a genetic component and whether any of her potential daughters would be at risk for one or both of these disorders. In the meantime, Jan is taking hormones, and she and Darryl are considering alternative modes of reproduction. Using the information in Figure 16.4, explain the reproductive options that are open to Jan and Darryl.

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?