Two related forms of muscular dystrophy—Duchenne muscular dystrophy (DMD) and Becker muscular dystrophy (BMD)—are both recessive, X-linked, single-gene conditions caused by point mutations, deletions, and insertion in the dystrophin gene. Each mutated form of dystrophin is one allele. Of the two diseases, DMD is much more severe. Given your knowledge of mutations, the genetic code, and translation, propose an explanation for why the two disorders differ greatly in severity.

Two related forms of muscular dystrophy—Duchenne muscular dystrophy (DMD) and Becker muscular dystrophy (BMD)—are both recessive, X-linked, single-gene conditions caused by point mutations, deletions, and insertion in the dystrophin gene. Each mutated form of dystrophin is one allele. Of the two diseases, DMD is much more severe. Given your knowledge of mutations, the genetic code, and translation, propose an explanation for why the two disorders differ greatly in severity.

Name: Two related forms of muscular dystrophy—Duchenne muscular dystrophy (D
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Description: Two related forms of muscular dystrophy—Duchenne muscular dystrophy (DMD) and Becker muscular dystrophy (BMD)—are both recessive, X-linked, single-gene conditions caused by point mutations, deletions, and insertion in the dystrophin gene. Each mutate

Human Heredity: Principles and Issues (MindTap Course List)

11th Edition

ISBN:9781305251052

Author:Michael Cummings

Publisher:Michael Cummings

Chapter15: Genomes And Genomics

Section: Chapter Questions

Problem 1QP: The gene controlling ABO blood type and the gene underlying nail-patella syndrome are said to show...

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Duchenne muscular dystrophy (DMD) is an X-linked recessive genetic disease caused by mutations in the gene that encodes dystrophin, a large protein that plays an important role in the development of normal muscle fibers. The Dystrophin gene is immense, spanning 2.5 million base pairs, and includes 79 exons and 78 introns. Many of the mutations that cause DMD produce premature stop codons, which bring protein synthesis to a halt, resulting in a greatly shortened and nonfunctional form of dystrophin. Some geneticists have proposed treating DMD patients by introducing small RNA molecules that cause the spliceosome to skip the exon containing the stop codon (A. Goyenvalle et al., 2004. Science 306:1796–1799). The introduction of the small RNAs will produce a protein that is somewhat shortened because an exon is skipped and some amino acids are missing, but it may still result in a protein that has some function. The small RNAs, antisense RNAs, used for exon skipping are complementary to…
Duchenne muscular dystrophy (DMD) is an X-linked recessive genetic disease caused by mutations in the gene that encodes dystrophin, a large protein that plays an important role in the development of normal muscle fibers. The dystrophin gene is immense, spanning 2.5 million base pairs, and includes 79 exons and 78 introns. Many of the mutations that cause DMD produce premature stop codons, which bring protein synthesis to a halt, resulting in a greatly shortened and nonfunctionalform of dystrophin. Some geneticists have proposed treating DMD patients by causing the spliceosome to skip the exon containing the stop codon. Exon skipping would produce a protein that is somewhat shortened (because an exon is skipped and some amino acids are missing), but might still result in a protein that had some function (A. Goyenvalle et al. 2004. Science 306:1796–1799). Propose a possible mechanism to bring about exon skipping for the treatment of DMD.
In McCune-Albright syndrome, fibrous connective tissue replaces bone, tan patches (café-au-lait spots) dot the skin, and hormone abnormalities cause early puberty and malfunction of the thyroid, pituitary, and adrenal glands. The phenotype is highly variable, and all patients are somatic mosaics for the mutation, which is in the gene GNAS1. Why is the condition seen only in mosaics?
There are two genetic disorders that result from mutation in imprinted genes: Prader-Willi syndrome and Angelman syndrome. Prader-Willi syndrome results from deletion of region 15q11-q13, which in healthy individuals is a region imprinted such that only the paternal copy is expressed. In the pedigree above, individual I-1 is heterozygous for a deletion of region 15q11-q13 and does not have Prader-Willi syndrome. Individuals I-2 and II-1 are both homozygous wild type for the region. Which individuals in the pedigree might have Prader-Willi syndrome? (Who could potentially have the syndrome, based on what alleles it is possible for them to inherit and express?) Question 9 options: Only II-2 could have Prader-Willi syndrome III-1 could have Prader-Willi syndrome in the presented pedigree; II-2 could only have had it if she were male Both II-2 and III-1 could have Prader-Willi syndrome II-2 could have…
There are two genetic disorders that result from mutation in imprinted genes: Prader-Willi syndrome, Angelman syndrome. Angelman syndrome results from deletion of UBE3A, which is a gene imprinted such that only the maternal copy is expressed. In the pedigree above, individual I-1 is heterozygous for a deletion of UBE3A and does not have Angelman syndrome. Individual I-2 is homozygous wild type for UBE3A. Which individuals in the pedigree are at risk for exhibiting Angelman syndrome, if any? (Who could potentially have the syndrome, based on what alleles it is possible for them to inherit and express?) Question 8 options: Only I-1 could have been at risk. If he does not have the syndrome, no one in the pedigree could. Only III-1 is at risk I-1, II-2, and III-1 are all at risk Only II-2 is at risk No one in the pedigree is at risk Both II-2 and III-1 are at…
Duchenne Muscular Dystrophy (DMD) is a disorder that primarily affects the function of skeletal muscles used for movement and cardiac muscles used for heart beating. Dystrophin is a protein encoded by a single gene, DMD, that is expressed in skeletal and cardiac muscle. Some forms of muscular dystrophy may be caused by different mutations in the DNA sequence of the DMD gene. Because the DMD locus is on the X chromosome, males are affected at higher rates. Two brothers, one of whom has DMD and one of whom does not, worked with their genetic counselor (Links to an external site.) to have their DMD gene sequenced to identify genetic variation that may explain why one brother was affected and the other not. Because DMD is a very long gene, a fictionalized, simplified model of the results is presented here (Figure 1). The actual DMD mRNA is about 16,000 base-pairs!------Consider single nucleotide polymorphism (SNP) #1 (Figure 1). Is this mutation likely to cause Duchenne muscular…
Campomelic dysplasia (CMD1) is a congenital humansyndrome featuring malformation of bone and cartilage.It is caused by an autosomal dominant mutation of agene located on chromosome 17. Consider the followingobservations in sequence, and in each case, draw whateverappropriate conclusions are warranted.(a) Of those with the syndrome who are karyotypically46,XY, approximately 75 percent are sex reversed,exhibiting a wide range of female characteristics.(b) The nonmutant form of the gene, called SOX9, isexpressed in the developing gonad of the XY male,but not the XX female.(c) The SOX9 gene shares 71 percent amino acid codingsequence homology with the Y-linked SRY gene.(d) CMD1 patients who exhibit a 46,XX karyotypedevelop as females, with no gonadal abnormalities.
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Prader-Willi syndrome is caused by a mutation in anautosomal maternally imprinted gene. Label the following statements as true or false, assuming that thetrait is 100% penetrant.a. Sons of affected males have a 50% chance of showing the syndrome.b. Daughters of affected males have a 50% chance ofshowing the syndrome.c. Sons of affected females have a 50% chance ofshowing the syndrome.d. Daughters of affected females have a 50% chanceof showing the syndrome.
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The gene controlling ABO blood type and the gene underlying nail-patella syndrome are said to show linkage. What does that mean in terms of their relative locations in the genome? What does it mean in terms of how the two traits are inherited with respect to each other?
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