Deck 6: Pedigree Analysis, Applications, and Genetic Testing

Question 1

If the characteristic followed in the pedigree is autosomal recessive, what is III-1's genotype?

A) either homozygous dominant or heterozygous
B) definitely heterozygous
C) definitely homozygous dominant
D) must be homozygous recessive
E) homozygous dominant since he is a male but a female would be heterozygous

Answer 1

B

Question 2

Which description of a Y-linked trait in humans is CORRECT?

A) All the sons of an affected father will be affected with the trait.
B) Half the sons of a mother whose father was affected with the trait will be affected.
C) Half the sons of an affected father will not be affected with the trait and the other half will be infertile.
D) All the daughters of an affected father will be phenotypically normal but half of their own sons will be affected with the trait.
E) The parents of an affected man likely were both phenotypically normal.

Answer 2

A

Question 3

What is/are the possible inheritance pattern(s) for the characteristic in Pedigree 1? Assume no new mutations and complete penetrance.

A) autosomal recessive only
B) autosomal dominant only
C) X-linked recessive only
D) X-linked dominant only
E) All of these are possible.

Answer 3

A

Question 4

Most pedigrees showing the hypothetical human trait show the following characteristics: • Females are affected twice as frequently as males.
• Affected fathers may have affected daughters but never affected sons.
• Half the children of affected mothers and normal fathers are affected.
What is the MOST likely mode of inheritance for this disorder?

A) autosomal recessive
B) autosomal dominant
C) X-linked recessive
D) X-linked dominant
E) Y-linked

Question 5

Most pedigrees showing the hypothetical human trait show the following characteristics: • Males and females are equally affected.
• Two unaffected parents can have an affected child.
• In families in which the parents are unaffected but the children are affected, one-fourth of the children are affected.
What is the MOST likely mode of inheritance for this disorder?

A) autosomal recessive
B) autosomal dominant
C) X-linked recessive
D) X-linked dominant
E) Y-linked

Question 6

Could the characteristics followed in the pedigree be caused by an X-linked recessive allele?

A) Yes, all individuals fit the X-linked recessive inheritance pattern.
B) No, the offspring of I-1 and I-2 contradict an X-linked recessive inheritance.
C) No, the offspring of I-3 and I-4 contradict an X-linked recessive inheritance.
D) No, the offspring of II-3 and II-4 contradict an X-linked recessive inheritance.
E) Possibly, but I-4 would have to be a heterozygous carrier if there is X-linked inheritance.

Question 7

Could the characteristic followed in the pedigree below be caused by an autosomal dominant disease? Why or why not?

A) Yes, all individuals fit the autosomal dominant inheritance pattern.
B) No, the offspring of I-1 and I-2 contradict an autosomal dominant inheritance.
C) No, the offspring of I-3 and I-4 contradict an autosomal dominant inheritance.
D) No, the offspring of II-3 and II-4 contradict an autosomal dominant inheritance.
E) Yes, the offspring of I-1and I-2 are consistent with an autosomal dominant inheritance pattern.

Question 8

In pedigree analysis, consanguinity refers to:

A) mating between two heterozygous carrier parents.
B) the realization that phenotypes between children and grandparents are often more closely related than between children and parents.
C) mating between two closely related parents.
D) a situation where the children of two parents are adopted.
E) a situation where only one individual in the entire pedigree is affected with the trait or disorder.

Question 9

In pedigree analysis, the proband is:

A) the individual having the trait or disorder from whom the pedigree is initiated.
B) the medical geneticist who analyzes the pedigree to find the mode of inheritance for the disorder.
C) the parents of the first child in the family to show the trait or disorder.
D) one of the grandparents or great grandparents who are in the first generation of the pedigree.
E) the most common software package that geneticists use to analyze pedigrees.

Question 10

The ability to roll the tongue is caused by a dominant allele. A woman is a "roller," but one of her parents is not. The woman is expecting a child with a man who is a "nonroller." What is the probability that their first child will be a "roller"?

A) 1/4
B) 0
C) 3/4
D) 1/2
E) 1

Question 11

If the characteristic followed in the pedigree is X-linked recessive allele, what is III-1's genotype?

A) hemizygous for a dominant allele
B) hemizygous for a recessive allele
C) definitely heterozygous
D) definitely homozygous dominant
E) either heterozygous or homozygous dominant

Question 12

Two parents are phenotypically normal, but one of their four biological children has a typical autosomal recessive trait. The other three children are phenotypically normal. It is very likely that:

A) the affected child is a girl.
B) the affected child is a boy.
C) the trait was expressed by one of the grandparents of the children.
D) the parents are both heterozygous for the trait.
E) if the affected child eventually marries a phenotypically normal spouse, all of their children will have the trait.

Question 13

Which statement is INCORRECT concerning an X-linked recessive trait in humans?

A) An affected man often has phenotypically normal parents.
B) All the sons of an affected woman will be expected to be affected.
C) An affected woman almost always has an affected mother.
D) An affected man usually has a mother who carries the recessive allele.
E) A phenotypically normal woman whose father was affected is likely to be heterozygous for the condition.

Question 14

If the pedigree below is for an autosomal recessive characteristic, which individuals are definitely heterozygous?

A) I-1, I-2, II-2, II-4, II-5
B) I-1, I-2, I-4, III-1
C) I-1, I-2, II-4, II-5, III-1
D) II-2, II-4, II-5, II-3
E) II-2, II-4, II-5, III-1

Question 15

Most pedigrees showing the hypothetical human trait show the following characteristics: • If a phenotypically normal woman with an affected father has children with an unaffected man, half of the sons and none of the daughters are affected.
• Affected females always have an affected father and an affected maternal grandfather.
• The trait is never passed from father to son.
What is the MOST likely mode of inheritance for this disorder?

A) autosomal recessive
B) autosomal dominant
C) X-linked recessive
D) X-linked dominant
E) Y-linked

Question 16

Most pedigrees showing the hypothetical human trait show the following characteristics: • Only males are affected.
• Affected fathers always pass the trait to sons.
What is the MOST likely mode of inheritance for this disorder?

A) autosomal recessive
B) autosomal dominant
C) X-linked recessive
D) X-linked dominant
E) Y-linked

Question 17

Which of the following is NOT a characteristic of X-linked recessive traits in humans?

A) More males than females are affected.
B) Approximately one-half of the sons of a female carrier are affected.
C) They cannot be passed from father to son.
D) Phenotypically normal daughters of affected men are always carriers.
E) Affected daughters always have an affected mother.

Question 18

Which term refers to mating between closely related people?

A) consanguinity
B) probanding
C) congenital
D) concordance
E) discordance

Question 19

Which of the following is NOT a typical characteristic of human traits that follow an autosomal recessive inheritance pattern?

A) They often "skip" generations.
B) They appear equally in males and females.
C) Parents of affected children are often phenotypically normal themselves.
D) When affected individuals marry phenotypically normal individuals, their children are often phenotypically normal.
E) All of the above are characteristic of autosomal recessive inheritance.

Question 20

The ability to roll the tongue is caused by a dominant allele. A woman is a "roller," but one of her parents is not. What is the woman's genotype?

A) homozygous dominant
B) heterozygous
C) homozygous recessive
D) either homozygous recessive or homozygous dominant
E) It cannot be determined from this information.

Question 21

Juliet and Bob have two children, Jack and Norma. No one in this family is red-green color blind, although Juliet sometimes has difficulty passing the color-vision part of the driving test. Norma has a color-blind son with Tom, who is not color blind. Draw a pedigree that includes all of this information. Below each person in the pedigree, write his or her genotype for the red-green color blindness gene, using B for the normal allele and b for the color blindness allele.

Question 22

The pedigree below shows the segregation of an autosomal dominant trait. If IV-1 marries IV-5, what is the probability that their first child will be affected? Assume that the homozygous mutant genotype is viable and has the same phenotype as the heterozygote.

A) 1/4
B) 1/2
C) 3/4
D) 3/8
E) 1/8

Question 23

The pedigree below shows a rare autosomal recessive trait segregating. What is the probability of the first child of a marriage between III-3 and III-7 being affected?

A) 1/12
B) 1/4
C) 1/8
D) 1/16
E) 1/24

Question 24

The pedigree below shows the sex-linked recessive inheritance of Nance-Horan syndrome, a rare Mendelian disorder in which affected persons have cataracts and abnormally shaped teeth. What is the probability that the first child of IV-6 and V-3 would have Nance-Horan syndrome?

A) ¹/₄
B) ¹/₂
C) 1/8
D) 3/16
E) ³/₄

Question 25

If the phenotype followed in Pedigree 3 is X-linked recessive, then what is the genotype of II-2? Assume no new mutations and complete penetrance.

A) homozygous dominant
B) heterozygous
C) homozygous recessive
D) hemizygous dominant
E) hemizygous recessive

Question 26

If the phenotype followed in Pedigree 3 is autosomal recessive, then what is the genotype of I-1? Assume no new mutations and complete penetrance.

A) homozygous dominant
B) heterozygous
C) homozygous recessive
D) hemizygous dominant
E) hemizygous recessive

Question 27

Draw a four-generation pedigree, following color blindness, using the following information: In generation I, neither parent is color blind. In generation II, a son (II-1) is color blind, a daughter (II-2) is not. II-2 and a man with normal color vision (II-3) have a daughter (III-1) who is not color blind. III-1 and a man with normal color vision (III-2) have a daughter (IV-1) who is not color blind. Write in all the genotypes that are known. Use symbols X^c and Y to follow the sex chromosomes and sex-linked genes.

Question 28

The pedigree below shows the segregation of an autosomal recessive trait. What is the probability that the child of III-1 and III-2 will be affected? Assume that individuals from outside the families are homozygous normal.

A) 1/9
B) 1/64
C) 1/36
D) 1/12
E) 1/16

Question 29

What is/are the possible inheritance pattern(s) for the characteristic in Pedigree 2? Assume no new mutations and complete penetrance.

A) autosomal recessive only
B) autosomal dominant only
C) X-linked recessive only
D) X-linked dominant only
E) All of these are possible.

Question 30

Tony, who is not diseased, has a sister with cystic fibrosis (CF). Neither of his parents has CF. Tony is expecting a child with Tina. Tina's family history is unknown. What is the probability that Tony is heterozygous for the CF gene? Explain your answer.

Question 31

Is it possible that the characteristic in the pedigree below could be X-linked recessive? If so, what is the genotype of each individual? If not, explain why not, giving specific genotypes. Use alleles A and a.

Question 32

Tony, who is not diseased, has a sister with cystic fibrosis (CF). Neither of his parents has CF. Tony is expecting a child with Tina. Tina's family history is unknown. Draw a pedigree that includes all of this information. Below each person in the pedigree, write his or her genotype or possible genotypes, using A for the normal CF allele and a for the disease-causing recessive allele.

Question 33

Is it possible that the characteristic in the pedigree below could be X-linked dominant? If so, what is the genotype of each individual? If not, explain why not, giving specific genotypes. Use alleles B and b.

Question 34

The pedigree below shows the segregation of an autosomal recessive trait. If III-3 and III-4 marry and have a child, what is the probability that this child will show the trait?

A) ¹/₄
B) 1/6
C) 1/8
D) ¹/₂
E) 2/3

Question 35

Is it possible that the characteristic in the pedigree below could be autosomal dominant? If so, what is the genotype of each individual? If not, explain why not, giving specific genotypes. Use alleles D and d.

Question 36

What is the MOST likely mode of inheritance in the pedigree below?

A) autosomal recessive
B) autosomal dominant
C) X-linked recessive
D) X-linked dominant
E) Y-linked

Question 37

June has two brothers with Becker muscular dystrophy (BMD), an X-linked recessive condition that allows affected males to survive into adulthood. Her parents are phenotypically normal. She marries Sheldon who also has BMD. June and Sheldon have a daughter. What is the probability that this daughter will have BMD?

A) near 0
B) 1/4
C) 1/2
D) 3/4
E) 1/8

Question 38

The pedigree below shows the segregation of an autosomal recessive trait in humans. Unless there is evidence to the contrary, assume that individuals who marry into the family do not carry the recessive allele. If IV-1 and IV-2 marry, what is the probability that their first child will have this trait?

A) 1/12
B) 1/16
C) 1/24
D) 1/36
E) 1/8

Question 39

What is the MOST likely mode of inheritance for the trait segregating in the pedigree below?

A) X-linked recessive
B) autosomal recessive
C) could be either X-linked recessive or autosomal recessive
D) X-linked dominant
E) autosomal dominant

Question 40

Assuming that it is not a Y-linked trait, suggest the MOST likely mode of inheritance for the rare trait shown in the pedigree below.

A) autosomal recessive
B) autosomal dominant
C) X-linked recessive
D) X-linked dominant
E) mitochondrial

Question 41

Researchers studying genetic determination of childhood asthma noted 65% concordance for monozygotic twin pairs in which at least one twin has asthma and 37% concordance for dizygotic twin pairs in which at least one twin has asthma.
a. Explain the meaning of 65% concordance for asthma in monozygotic twins.
b. Interpret the difference in concordance for asthma between monozygotic and dizygotic twins.
c. If genes do influence childhood asthma, how is that 35% of monozygotic twin pairs are discordant for asthma?

Question 42

Assume that the concordance values for a particular disease are 63% for monozygotic twins and 36% for dizygotic twins. Which of the following are TRUE? (Select all that apply.)

A) Environmental factors are important in susceptibility to this disease.
B) Genetic factors are important in susceptibility to the disease with monozygotic twins but not with dizygotic twins.
C) Genetic factors are not important in susceptibility to this disease.
D) Genetic factors are important in susceptibility to this disease.
E) Environmental factors are important in susceptibility to this disease with dizygotic twins but not with monozygotic twins.

Question 43

A trait is caused by a rare dominant autosomal allele with full penetrance. Practically all individuals with the trait are heterozygous and result from matings between affected and normal individuals. What would be the expected concordance values for monozygotic and dizygotic twins?

A) 100% for both types of twins
B) 100% for monozygotic twins and 90% for dizygotic twins
C) about 90% for both types of twins
D) 100% for monozygotic twins and 50% for dizygotic twins
E) 75% for monozygotic twins and 25% for dizygotic twins

Question 44

Is it possible that the characteristic in the pedigree below could be autosomal dominant? If so, what is the genotype of each individual? If not, explain why not, giving specific genotypes. Use alleles D and d.

Question 45

In an effort to identify the influence of genetic factors on both Type 1 diabetes and Type II diabetes, researchers calculated concordance rates for monozygotic twins. Concordance rates of 30-50% have been found for Type I diabetes with concordance rates of 80% for Type II. For both kinds of diabetes, dizygotic concordance rates were about 15%. What does this information suggest concerning the relative effect of genetic and environmental factors for each type of diabetes?

A) Genetic factors have little or no role in the occurrence of Type I diabetes.
B) Type II diabetes is primarily determined by nongenetic factors.
C) Genetic influences exert a larger role in Type II diabetes than in Type I diabetes.
D) Type II diabetes appears to be caused by a single unidentified gene.
E) Environmental factors have no role in the occurrence of either type of diabetes.

Question 46

Which of the following statements is NOT true concerning newborn screening?

A) It is normally done soon after the birth of a child.
B) It is particularly important to test for serious conditions where there is no treatment available.
C) Most newborn testing is done by collecting a small amount of an infant's blood and then using it for analysis to detect specific genetic disorders.
D) The genetic disorder phenylketonuria is one of the conditions usually tested for with newborn screening.
E) All of the statements are true.

Question 47

Lucy is 16 weeks pregnant and undergoes maternal serum screening to measure her maternal alpha fetoprotein levels (AFP). Her AFP level is several times higher than normal levels. For which of the following disorders should Lucy be offered additional testing?

A) trisomy 21, a chromosome abnormality
B) sickle-cell disease, an autosomal recessive disorder
C) spina bifida, a neural-tube defect
D) hemophilia A, a sex-linked recessive disorder
E) Lucy does not need additional testing for any disorder.

Question 48

In one study with both monozygotic and dizygotic twins, the concordance value for a neurological disorder was 100% for monozygotic twins. Which of the following statements is CORRECT?

A) The concordance value for dizygotic twins will be also 100%.
B) There will be no phenotypic variation in susceptibility for the disorder for all the pairs of twins in the study.
C) The concordance value for dizygotic twins will be 25%.
D) For dizygotic twins, all the variation in susceptibility for the disorder will be due to environmental factors.
E) Most of the variation in susceptibility for the disorder for monozygotic twins is likely due to genetic factors assuming that the concordance value for dizygotic twins is significantly less than 100%.

Question 49

A trait is caused by a rare recessive autosomal allele with full penetrance. Practically all individuals with the trait result from matings between normal individuals. What would be the expected concordance values for monozygotic and dizygotic twins?

A) 100% for both types of twins
B) 100% for monozygotic twins and 50% for dizygotic twins
C) about 50% for both types of twins
D) 100% for monozygotic twins and 75% for dizygotic twins
E) 100% for monozygotic twins and 25% for dizygotic twins

Question 50

Which of the following is NOT correctly identified as an advantage is using amniocentesis?

A) It can be used to detect chromosome abnormalities prenatally in the fetus.
B) In some cases, it can be used to obtain fetal DNA so that tests can be done to determine if the fetus may have a particular genetic disorder.
C) It can normally be done as early as the sixth week of pregnancy.
D) It has a somewhat lower risk of complications than chorionic villus sampling.
E) All of these are advantages with the use of amniocentesis.

Question 51

Heterozygous genetic screening is used mainly to:

A) detect genetic disorders in newborn infants.
B) detect adult members of a particular population who may be heterozygous carriers for recessive disorders.
C) detect in healthy adults the presence of a mutant allele that may predispose them to some serious health problem later in life.
D) detect fetuses who may be heterozygous carriers for recessive disorders and may eventually be at risk of having children of their own with these disorders.
E) detect adults that may be heterozygous for serious autosomal dominant disorders.

Question 52

If monozygotic and dizygotic twins have the same concordance value for a trait, which of the following is TRUE?

A) Genetic factors are more important than environmental factors for the trait.
B) The trait is probably influenced by numerous genes.
C) The trait will more likely appear in males than in females.
D) The trait will be passed on from fathers to their daughters but not to their sons.
E) The trait is entirely due to environmental factors.

Question 53

Tony, who is not diseased, has a sister with cystic fibrosis (CF). Neither of his parents has CF. Tony is expecting a child with Tina. Tina's family history is unknown. If the frequency of heterozygotes in the general population is 1/50, what is the probability that Tony and Tina's child will have CF? Explain each factor in your calculation.

Question 54

Is it possible that the characteristic in the pedigree below could be X-linked recessive? If so, what is the genotype of each individual? If not, explain why not, giving specific genotypes. Use alleles A and a.

Question 55

Explain the principle behind using concordance values for monozygotic (MZ) and dizygotic (DZ) twins to determine the influence of genetic factors on individual differences for a trait.

Question 56

Which of the following is NOT normally used to study the inheritance of human traits or disorders?

A) pedigree analysis
B) twin studies
C) adoption studies
D) All of these are used in the study of human traits or disorders.
E) None of these is used in the study of human traits or disorders.

Question 57

Explain what the following data say about the genetic and environmental influence on each characteristic. How did you interpret these data? (MZ = monozygotic twins and DZ = dizygotic twins.) $$\begin{array} { | l | c c } \hline & { \text { Concordance in } } \\\hline \text { Trait } & \text { MZ } & \text { DZ } \\\hline \text { Right- or left-handedness } & 80 & 75 \\\hline \text { Manic depression } & 80 & 20 \\\hline\end{array}$$

A) Handedness and manic depression both have a strong genetic basis and little or no environmental basis.
B) Handedness and manic depression are both strongly affected by environmental factors with little or no genetic basis.
C) Handedness and manic depression are strongly affected by both environmental factors and genetic factors.
D) Handedness is strongly affected by environmental factors with little or no genetic basis, while manic depression is significantly affected by genetic factors.
E) Handedness is significantly affected by both environmental and genetic factors, while manic depression is significantly affected by environmental factors with little genetic basis.

Question 58

Below are concordance rates for five different human disorders studied in monozygotic (MZ) and dizygotic (DZ) twins. $$\begin{array} { c l c } \hline & { \text { Concordance } } \\\text { Disorder } & \text { MZ } & \text { DZ } \\& & \\\hline \text { A } & 100 \% & 50 \% \\\text { B } & 17 \% & 16 \% \\\text { C } & 56 \% & 11 \% \\\text { D } & 100 \% & 25 \% \\\text { E } & 50 \% & 100 \%\end{array}$$ One of the above disorders is in part caused by significant genetic effects. In addition to a significant genetic contribution toward the disorder, there are also significant environmental effects that contribute toward the disorder phenotype. To which of the above disorders would this description MOST likely apply?

A) A
B) B
C) C
D) D
E) E

Question 59

Is it possible that the characteristic in the pedigree below could be X-linked dominant? If so, what is the genotype of each individual? If not, explain why not, giving specific genotypes. Use alleles B and b.

Question 60

Imagine that a human characteristic is determined by genotype only, with no environmental influence. Based on the amount of shared genetic information in MZ (monozygotic) and DZ (dizygotic) twins, what would you expect the concordance values to be in these two sets of twins?

A) The concordance values would be near 100% for both types of twins.
B) The concordance values would be near 50% for both types of twins.
C) The concordance values should be close to 100% for MZ twins and a concordance value much less for DZ twins.
D) The concordance values should be close to 50% for MZ twins and about 25% for DZ twins.
E) The concordance values should be close to 25% for MZ twins and about 75% for DZ twins.

Question 61

The American College of Medical Genetics recommends mandatory screening of newborn infants for 29 conditions, and many states have adopted this recommendation into law.
a. Explain the benefits of mandatory newborn screening for medical conditions.
b. Why might some people be concerned about or even opposed to mandatory screening of newborns?
c. Do you support mandatory screening of newborn infants for genetic disorders? Defend your position with facts and arguments.

Question 62

To establish a successful and cost-effective screening program for detecting adult heterozygous carriers of an autosomal recessive disease, which of the following is NOT important?

A) Detection of the disorder is possible in the fetus.
B) The disease is clinically significant.
C) A high-risk population can be identified.
D) Genetic counseling is provided with the testing.
E) An effective treatment is available for the disorder.

Question 63

This form of prenatal testing is most commonly performed between the 10th week and 12th week of pregnancy and involves the insertion of a soft plastic into the vagina to obtain cells.

A) chorionic villus sampling
B) preimplantation genetic analysis
C) amniocentesis
D) heterozygote screening
E) presymptomatic screening

Question 64

Both members of an expecting couple are carriers of Tay-Sachs disease, which is an autosomal recessive condition that causes deterioration of nervous function within several months after birth and usually death by age 4. The couple wants to avoid having a child with Tay-Sachs disease, and a DNA test is available to detect the mutant allele. It is early in the pregnancy, and the couple is willing to abort the fetus if it is homozygous for the allele that causes Tay-Sachs disease. However, the couple wishes to have the abortion performed as early as possible if one is to be done. Which would be the MOST appropriate test to determine the genotype of the fetus?

A) amniocentesis
B) newborn screening
C) preimplantation genetic diagnosis
D) heterozygote screening
E) chorionic villus sampling

Question 65

Heterozygote screening normally involves:

A) testing healthy individuals to see if they possess mutant alleles that may make them ill later in life.
B) testing newborn infants to see if they have a genetic disorder so that they can be treated immediately.
C) examining fetal cells to see if they have a serious genetic disorder so that the pregnancy can be terminated if the parents so desire.
D) testing to determine if two parents are related to each other.
E) testing adult members of a particular population to identify heterozygous carriers for a recessive disorder.

Question 66

Today, more than 1200 genetic tests are available to doctors and patients for use in diagnosis and treatment of health conditions, and more will become available in the near future. Genetic testing is becoming more common in medical practice, and genetic testing is expected to become commonplace. Explain the complications that are associated with genetic testing and why specialized genetic counselors are needed in medical practice.

Question 67

Which of the following conditions is MOST commonly screened for in maternal blood tests?

A) phenylketonuria and chromosome abnormalities
B) Tay-Sachs disease and neural-tube defects
C) cancer and multiple sclerosis
D) chromosome abnormalities and neural-tube defects
E) None of the answers is correct.

Question 68

(a) What is a direct-to-consumer genetic test? (b) What are some advantages of direct-to-consumer tests? (c) What are some disadvantages or problems associated with these tests? (d) Do you think states and/or the federal government should regulate direct-to-consumer genetic testing? Defend your position with facts and arguments.

Question 69

Phenylketonuria (PKU) is an autosomal recessive condition that can lead to mental retardation. It is caused by an enzyme deficiency that interferes with phenylalanine metabolism, causing a by-product to accumulate to levels that are toxic to brain development. Intellectual disability due to PKU can be prevented by a special diet that strictly restricts intake of phenylalanine but the diet must be started soon after birth to be effective. Which of the following would be the MOST appropriate and cost-efficient way of identifying individuals who need the special diet?

A) heterozygote screening
B) newborn screening
C) presymptomatic testing
D) prenatal diagnosis
E) amniocentesis

Question 70

Suppose that a harmful autosomal recessive condition is found at a particularly high frequency within a certain population. Public health officials would like to reduce the incidence of the condition in the population using genetic testing and genetic counseling. Which of the following programs would be MOST appropriate and most effective in achieving the desired outcome?

A) presymptomatic genetic testing
B) heterozygote screening
C) newborn screening
D) preimplantation genetic diagnosis
E) amniocentesis

Question 71

Fetal cell sorting is a(n):

A) method of obtaining fetal cells through amniocentesis.
B) method of obtaining fetal cells through chorionic villus sampling.
C) procedure for detecting and separating fetal cells from maternal blood cells.
D) invasive procedure that allows a physician to directly take blood from the fetus to analyze for genetic conditions.
E) method where a fetus who has a genetic condition can be treated before birth by providing it with healthy fetal cells.

Question 72

Which of the following are typical reasons why individuals or couples may seek genetic counseling? (Select all that apply.)

A) A husband and wife are closely related and they wish to have children.
B) A husband is 15 years older than his wife and they wish to have children.
C) A person knows of a genetic disease in the family.
D) A couple has given birth to a child with a genetic disease.
E) A couple experiences difficulties in achieving a successful pregnancy.

Question 73

This form of prenatal testing is most commonly performed between the 15th week and 18th week of pregnancy.

A) chorionic villus sampling
B) preimplantation genetic analysis
C) amniocentesis
D) heterozygote screening
E) presymptomatic screening

Question 74

Describe at least two reasons why testing for a genetic condition might be advantageous.

Question 75

A maternal blood screening test carried out in the second month of a pregnancy indicates a level of $\alpha$ -fetoprotein that is significantly higher than normal.
a. What is $\alpha$ -fetoprotein?
b. What does a higher than normal level of $\alpha$ -fetoprotein in the mother's blood indicate?
c. Critique the maternal blood screening test-specifically, what are its limitations?
d. Given the limitations of the tests, why are they so commonly ordered?
e. If you were the doctor who ordered this test, how would you proceed?

Question 76

Explain what it means for a genetic counselor to use "nondirected counseling."

Question 77

Preimplantation genetic testing involves:

A) testing a newborn infant for a genetic disorder immediately after birth.
B) testing a single cell of an early embryo for a genetic disorder before the embryo is considered for implantation into the mother's uterus.
C) testing multiple sperm from a man who is heterozygous for a serious genetic disorder and then using only sperm that have normal alleles for in vitro fertilizations.
D) removing cells from a fetus, testing them for a genetic disorder, and then allowing abnormal fetuses to be aborted.
E) testing primary oocytes (eggs) for genetic disorders before using them for in vitro fertilizations.

Question 78

Which of the following statements concerning chorionic villus sampling are TRUE? (Select all that apply.)

A) A karyotype can be made from fetal cells.
B) It is usually performed between the 10th and 12th weeks of pregnancy.
C) It has fewer complications than does amniocentesis.
D) Biochemical analyses can be performed on fetal cells.
E) The fetal cells obtained usually do not need to be cultured.