lydactyly – extra fingers or toes–is one symptom of Ellis-van Creveld syndrome. The syndrome is commonly found among the Old Order Amish of Pennsylvania, a population that experiences the “founder effect”. This disease is more concentrated among the Amish because they marry within their own community, which prevents new genetic variation from entering

Zoe has cystic fibrosis. Which of the following is the most likely explanation? Zoe probably inherited one faulty allele from her father, who is a earner, and one normal allele from her mother. Zoe probably inherited one faulty allele from her mother, who must also have cystic fibrosis, and one normal allele from her father. Zoe must have inherited faulty alleles from both parents, both of whom must also have cystic fibrosis, Zoe must have inherited faulty alleles from both parents, both of whom are earners.

A recognized set of symptoms that characterize a genetic disorder is a(n) _______. a. syndrome b. disease c. abnormality d. inheritance pattern

What kind of diseases are studied using genome-wide association studies? a. viral diseases b. single-gene inherited diseases c. diseases caused by multiple genes d. diseases caused by environmental factors

Cystic fibrosis is an autosomal disease that mainly affects the white population, and 1 in 20 whites are heterozygotes. Genetic testing can diagnose heterozygotes. Should a genetic screening program for cystic fibrosis be instituted? Should the federal government fund it? Should the program be voluntary or mandatory, and why?

The Joneses were referred to a clinical geneticist because their 6-month-old daughter was failing to grow adequately and was having recurrent infections. The geneticist took a detailed family history (which was uninformative) and a medical history of their daughter. He discovered that their daughter had a history of a constant cough and wheeze that was becoming progressively worse, had difficulty gaining weight (failure to thrive), and had an extensive history of yeast infection (thrush) in her mouth. The geneticist did a simple blood test to check their daughters white blood count and determined that she had severe combined immunodeficiency (SCID). The geneticist explained that SCID is an immune deficiency that causes a marked susceptibility to infections. The defining characteristic is usually a severe defect in both the T- and B-lymphocyte systems. This results in one or more infections within the first few months of life that are serious and may even be life-threatening. Based on the family history, it was possible that their daughter had inherited a mutant allele from each of them and therefore was homozygous for a gene that causes SCID. If so, each time the Joneses had a child, there would be a 25% chance that the child would have SCID. Prenatal testing is available to determine whether the developing fetus has SCID. If the Joneses want to be certain that their next child will not have SCID, what types of reproductive options do you think they have?

Figure 13.4 Which of the following statements is true? Recombination of the body color and red/ cinnabar eye alleles will occur more frequently than recombination of the alleles for wing length and aristae length. Recombination of the body color and aristae length alleles will occur more frequently than recombination of red/brown eye alleles and the aristae length alleles. Recombination of the gray/black body color and long/short aristae alleles will not occur. Recombination of the red/brown eye and long/short aristae alleles will occur more frequently than recombination of the alleles for wing length and body color.

Birth Defects and Multiple Births A woman who carries multiple offspring at the same time increases the risk of some birth defects. FIGURE 42.18 shows the results of Yiwei Tang's study of birth defects reported in Florida from 1W6 to 2000. Tang compared the incidence of various defects among single and multiple births. She calculated the relative risk for each type of defect based on type of birth, and corrected for other differences that might increase risk such as maternal age, income, race, and medical care during pregnancy. A relative risk of less than 1 means that multiple births pose less risk of that defect occurring. A relative risk greater than 1 means multiples are more likely to have a defect. FIGURE 42.18 Prevalence, per 10,000 live births, of various types of birth defects among multiple aria single births. Relative risk for each defect is given after researches adjusted for the motor's age, race, previous adverse pregnancy experience, education, Medicaid participation during pregnancy, as well as the infant's sex and number of siblings. 4. Does a multiple pregnancy increase the relative risk of chromosomal defects in offspring?

SCIENCE, TECHNOLOGY, AND SOCIETY Imagine that you are a genetic counselor. What advice or suggestions might you give in the following situations? (a) A couple has come for advice because the woman had a sister who died of Tay-Sachs disease. (b) A young man and woman who are not related are engaged to be married. However, they have learned that the mans parents are first cousins, and they are worried about the possibility of increased risk of genetic defects in their own children. (c) A young womans paternal uncle (her fathers brother) has hemophilia A. Her father is free of the disease, and there has never been a case of hemophilia A in her mothers family. Should she be concerned about the possibility of hemophilia A in her own children? (d) A 20-year-old man is seeking counseling because his father was recently diagnosed with Huntingtons disease. (e) A 45-year-old woman has just been diagnosed with Huntingtons disease. She says she will not tell her college-age sons because of the burden it will place on them. Given that the woman, not her sons, is your client, do you have a duty to inform the sons? Explain your reasoning.

The reason spontaneous mutations do not have an immediate effect on allele frequencies in a large population is that: a. mutations are random events, and mutations may be eitherbeneficial or harmful. b. mutations usually occur in males and have little effect oneggs. c. many mutations exert their effects after an organism hasstopped reproducing. d. mutations are so rare that mutated alleles are greatlyoutnumbered by nonmutated alleles. e. most mutations do not change the amino acid sequence of aprotein.