To review:
Whether the statements are accurate with regard to the genetic basis of human disease.
A. Two copies of a mutant allele should be inherited to have a disease.
B. Genetic predisposition refers to an individual who has inherited more than one allele that results in the development of the disease.
C. Genetic predisposition related disease may be passed from parent to offspring.
D. The genetic basis of a disease is always more important than itsenvironment.
Introduction:
Phenylketonuria (PKU) is a genetic disorder which is inherited by the offspringfrom parents. Mutation in the PAH (phenylalanine hydroxylase) gene is the reason for PKU, and results in decreased levels of enzyme phenylalanine hydroxylase. It is an inborn error of
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Genetics: Analysis and Principles
- Sickle-cell anemia is an interesting genetic disease. Normal homozygous individials (SS) have normal blood cells that are easily infected with the malarial parasite. Thus, many of these individuals become very ill from the parasite and many die. Individuals homozygous for the sickle-cell trait (ss) have red blood cells that readily collapse when deoxygenated. Although malaria cannot grow in these red blood cells, individuals often die because of this genetic defect causes deformation of red blood cells. However, individuals with the heterozygous condition (Ss) have some sickling of red blood cells, but generally not enough to cause mortality. In addition, malaria cannot survive well within these "partially defective" red blood cells. Thus, heterozygotes tend to survive better than either of the homozygous conditions. Assuming HWE, if 9% of an African population is born with a severe form of sickle-cell anemia (ss), what percentage of the population will be more resistant to malaria…arrow_forwardSickle-cell anemia is an interesting genetic disease. Normal homozygous individials (SS) have normal blood cells that are easily infected with the malarial parasite. Thus, many of these individuals become very ill from the parasite and many die. Individuals homozygous for the sickle-cell trait (ss) have red blood cells that readily collapse when deoxygenated. Although malaria cannot grow in these red blood cells, individuals often die because of the genetic defect. However, individuals with the heterozygous condition (Ss) have some sickling of red blood cells, but generally not enough to cause mortality. In addition, malaria cannot survive well within these "partially defective" red blood cells. Thus, heterozygotes tend to survive better than either of the homozygous conditions. 11% of an African population is born with a severe form of sickle-cell anemia (ss), What percentage of the population will be more resistant to malaria because they are heterozygous (Ss) for the sickle-cell…arrow_forwardSickle-cell anemia is an interesting genetic disease. Normal homozygous individials (SS) have normal blood cells that are easily infected with the malarial parasite. Thus, many of these individuals become very ill from the parasite and many die. Individuals homozygous for the sickle-cell trait (ss) have red blood cells that readily collapse when deoxygenated. Although malaria cannot grow in these red blood cells, individuals often die because of the genetic defect. However, individuals with the heterozygous condition (Ss) have some sickling of red blood cells, but generally not enough to cause mortality. In addition, malaria cannot survive well within these "partially defective" red blood cells. Thus, heterozygotes tend to survive better than either of the homozygous conditions. 11% of an African population is born with a severe form of sickle-cell anemia (ss), What is the frequency of the dominant allele? Please show your work in order to receive credit.arrow_forward
- Sickle-cell anemia is an interesting genetic disease. Normal homozygous individials (SS) have normal blood cells that are easily infected with the malarial parasite. Thus, many of these individuals become very ill from the parasite and many die. Individuals homozygous for the sickle-cell trait (ss) have red blood cells that readily collapse when deoxygenated. Although malaria cannot grow in these red blood cells, individuals often die because of the genetic defect. However, individuals with the heterozygous condition (Ss) have some sickling of red blood cells, but generally not enough to cause mortality. In addition, malaria cannot survive well within these "partially defective" red blood cells. Thus, heterozygotes tend to survive better than either of the homozygous conditions. 11% of an African population is born with a severe form of sickle-cell anemia (ss), What is the frequency of the recessive allele? Please show your work in orderarrow_forwardFor the following diseases, describe the best technique for diagnosing them. Please make sure you include how you would tell someone with the disease from someone without the disease. B. Factor V Leiden thrombophilia is caused by a point mutation at position 1691 in exon 10 of the Factor V clotting factor gene that changes an arginine into a glutamine. This change removes one of the cleavage sites for activated protein C and leads to an increased tendency to clot.arrow_forwardPancreatic cancer is clearly inherited as an autosomal dominant trait in the family illustrated in Figure 23.1. Yet most cases of pancreatic cancer are sporadic, appearing as isolated cases in families with no obvious inheritance. How can a trait be strongly inherited in one family and not inherited in another?arrow_forward
- Gene mutations can be classified in two major ways:(1) hereditary or germline mutations that are inherited from a parent and are present throughout a person’s life in virtually every cell in the body.(2) acquired or somatic mutations that occur at some time during a person’s life and are present only in certain cells, not in every cell in the body.If there is no family history of a particular disease but a child has the disease then it may have arisen due to a(n) ________ mutation early during development. A) acquired B) inherited C) silent D) transitionarrow_forwardConsider an autosomal recessive disease in which an individual must inherit two recessive alleles to display the disease phenotype. What is the probability that a woman who is a heterozygous for the trait and a man who is homozygous for the dominant allele will produce an offspring with the autosomal recessive phenotype? Assume no new mutations occur. Select one 1.) 100% 2.)25% 3.) 0% 4.)50% 5.) More information is neededarrow_forwardParents who both have "sickle-cell trait", i.e, are heterozygous for HbS have a child who is tested at birth, and is found to be homozygous for HbS (both alleles affected). What is the molecular reason why the child presents with no symptoms until 6 months of age? a.) the mutation affects the beta chain, which is not dominant at birth b.) the mutation affects the alpha chain, which is not dominant at birth c.) babies cannot be exposed to low oxygen that triggers symptoms d.) babies cannot be exposed to high oxygen that triggers symptomsarrow_forward
- A man and a woman have a child with cystic fibrosis. Neither parent has cystic fibrosis. How could this happen? a) Both parents carry the cystic fibrosis allele, and each passed that allele to their child. b) The child had a spontaneous mutation on both copies of their CFTR alleles, leading to cystic fibrosis. c) One parent gave the child two copies of the cystic fibrosis CFTR allele. c) One parent gave the child a wild type CFTR allele, and the other parent gave them a cystic fibrosis CFTR gene.arrow_forwardpeople with osteogenesis imperfecta have a dominant mutation in one of the two genes that produce type 1 collagen. people with OI have weak bones, bkuish color in teh whites of eyes, and a variety of afflictions that cause weakness in their joint and teeth. However, some people can carry the mutation but have no symptoms. Thus, families can unknowingly transmit the mutation but does not express the OI phenotype. This is an example of which of the following? a. incomplete penetrance b. variable expressivity c. epistasis d. incomplete dominancearrow_forwardAchondroplasia is an autosomal dominant disorder characterized by disproportionate short stature: the legs and arms of people with achondroplasia are short compared with the head and trunk. The disorder is due to a base substitution in the gene, located on the short arm of chromosome 4, that encodes fibroblast growth factor receptor 3 (FGFR3). Although achondroplasia is clearly inherited as an autosomal dominant trait, more than 80% of the people who have achondroplasia are born to parents with normal stature. This high percentage indicates that most cases are caused by newly arising mutations; these cases (not inherited from an affected parent) are referred to as sporadic. Studies have demonstrated that sporadic cases of achondroplasia are almost always caused by mutations inherited from the father (paternal mutations). In addition, the occurrence of achondroplasia is higher among the children of older fathers; approximately 50% of children with achondroplasia are born to fathers…arrow_forward
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