WHIM syndrome is a disease of the immune system resulting in warts and frequent infections. The disease is caused by a dominant gain-of-function mutation in a gene on chromosome 2 called CXCR4. A 38-year-old woman suffering with WHIM syndrome her entire life was suddenly and mysteriously cured. Genome analysis of her blood precursor cells (stem cells) revealed that many of these cells had a chromosome 2 that had undergone chromotripsis—a rare (and poorly understood) process where a chromosome is “shattered” into small pieces that are subsequently stitched back together in random order, resulting in many deletions and inversions. Explain how chromotripsis of chromosome 2 in a blood stem cell could have cured the woman of WHIM syndrome.
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ND STONY BROOK UNIVERSITY LOOSELEAF GENETICS: FROM GENES TO GENOMES
- Cystic fibrosis is a recessive disease that affects many parts of the body, but primarily presents itself through difficulty breathing and through cysts in the pancreas. It is caused by mutations in the gene CFTR. What chromosome is the gene on?arrow_forwardAn STR on chromosome 5 is very closely linked to a gene involved in a dominant metabolism disorder (one one copy of the mutation causes the disease). There are four different alleles of the STR (Q, B, S, and L), each with different numbers of GATCTCG repeats. The S allele has 2 repeats, the B allele has 7 repeats, the Q allele has 10 repeats, and the L allele has 5 repeats. Part 1 Lane 1 of the gel shown below indicates the locations of PCR products corresponding to all four STR alleles when run together in one lane. DNA was loaded into the wells at the top of the gel. Move the letter of each allele to its correct position at the left of Lane 1 to indicate where each allele runs on the gel. 0000 Gabriel Andre Lane 1 O Maria Andre Maria Juliana B L Part 2 Andre and Maria are the parents in this family; all others shown on the gel are children. Daughter Juliana is born with the metabolism disorder, but daughter Camila does not have the disorder. Assuming no recombination between the STR…arrow_forwardThe homologous chromosome pairs in our cells do not carry identical sequences in all loci. This heterozygosity (difference between the two.copies) can be altered in cancer: in fact, loss of heterozygosity at many loci is observed in cancer cells, through an increase in either homozygosity (two identical copies) or hemizygosity (i.e. loss of one copy). Researchers can take advantage of this loss of heterozygosity in cancer cells to identify genomic loci that contain cancer-critical genes. What type of gene would you expect to find in chromosomal regions with a loss of heterozygosity? Proto-oncogenes or tumour suppressor genes? Choose the correct answer here Proto-oncogenes Tumour Suppressor genesarrow_forward
- In humans, chromosome 16 sometimes has a heavily stained area near the centromere. This feature can be seen in a microscope, but otherwise has no effect on the phenotype of the person carrying it. When such a “blob" exists on a given copy of chromosome 16, it is a constant feature of that chromosome and is inherited. A couple conceived a child, but the fetus had multiple abnormalities and was miscarried. e.g., The fetus had three copies of chromosome 16, where 2 of the 3 copies of chromosome 16 had large blobs. Both of the mother's copies of chromosome 16 lacked blobs, but the father was heterozygous for blobs. The fetus was formed from a fertilization event that included a gamete produced by the in which nondisjunction occurred during the meiotic division. Select an answer and submit. For keyboard navigation, use the up/down arrow keys to select an answer. a mother; first. mother; second. father; first. C Your answer d father; second. E3 Fullso L e Insufficient information is provided…arrow_forwardIn humans, chromosome 16 sometimes has a heavily stained area in the long arm near the centromere. This feature can be seen through the microscope but has no effect on the phenotype of the person carrying it. When such a “blob” exists on a particular copy of chromosome 16, it is a constant feature of that chromosome and is inherited. A couple conceived a child, but the fetus had multiple abnormalities and was miscarried. When the chromosomes of the fetus were studied, it was discovered that it had three copies of chromosome 16 (it was trisomic for chromosome 16), and that two of the three chromosome 16s had large blobs. Both chromosome 16 homologs in the mother lacked blobs, but the father was heterozygous for blobs. Which parent experienced nondisjunction, and in which meiotic division did it occur?arrow_forwardA girl and a boy were born to a young married couple. The girl is absolutely healthy. The examination of the boy's karyotype has shown 46 chromosomes. But one of the chromosomes of the 15th pair is longer than normal as a part of a chromosome from the 21st pair has joined it. How many autosomes and sex chromosomes are in the boy's karyotype? Name the type of the mutation. Is it possible to consider this pathology an inherited disorder?arrow_forward
- The Hemoglobin gene has two very common alleles: HbS and HbA. Bob’s professor asks him to draw the chromosomes for an individual that is HbSHbA and label the alleles. Bob draws this (below). Explain why Bob is wrong and then draw it correctly. FOXP2 is a gene in humans; humans that have mutated copies of FOXP2 often have trouble speaking. It is on Chromosome 7, which is about 160 million base pairs long. FOXP2 is at position 115 million base pairs. Which of the drawings below appropriately diagrams the location of FOXP2? Why?arrow_forwardFriedreich ataxia (FRDA) is an autosomal recessive, neurodegenerative disease that causes a lack of voluntary coordination of muscle movements. Affected individuals are homozygous for an unusually large number (expansion) of repeats of a trinucleotide sequence (GAA) in the first intron of the X25 gene. Unaffected individuals typically have between 7 and 38 repeats of the trinucleotide (GAAGAAGAAGAA…). FRDA patients have anywhere from 66 to over 1,700 repeats. To understand how the GAA trinucleotide expansion leads to FRDA, researchers looked at X25 gene expression by extracting RNA from affected and unaffected patients and doing a northern blot analysis (see the figure below): In panel “a,” the researchers used a probe to detect X25 mRNA. In panel “b,” the researchers used a probe on a duplicate of the original blot to detect human GAPDH mRNA (GAPDH is an enzyme involved in glycolysis). The sample labeled “YR” is mRNA from yeast cells that was used as a control. Explain…arrow_forwardDuchenne 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…arrow_forward
- A defective gene on chromosome 15 causes Tay-Sachs disease. It is a central nervous system neurodegenerative disease that most often affects infants, though older children and adults can have late-onset forms of the disease. The defective gene prevents the body from making a protein called hexosaminidase A. Without, hexosaminidase A, chemicals called gangliosides build up in the nerve cells of the brain, destroying brain cells. Pedigree information regarding the incidence of Tay-Sachs within a family is depicted above. The row below that indicates the genotypes of individuals II-1, II-2, and III-1 is Select one: a. II-1 II-2 III-1 Aa Aa aa b. II-1 II-2 III-1 XAY XAXa XAXa c. II-1 II-2 III-1 XAY XAXA XaXa d. II-1 II-2 III-1 AA aa Aaarrow_forwardOrangutans are an endangered species in their natural environment (the islands of Borneo and Sumatra), and so a captive-breeding program has been established using orangutans currently held in zoos throughout the world. One component of this program is research into orangutan cytogenetics. This research has shown that all orangutans from Borneo carry one form of chromosome 2, as shown in the accompanying diagram, and all orangutans from Sumatra carry the other form. Before this cytogenetic difference became known, some matings were carried out between animals from different islands, and 14 hybrid progeny are now being raised in captivitya. What term or terms describe the differences between these chromosomes? b. Draw the chromosomes 2, paired in the first meiotic prophase, of such a hybrid orangutan. Be sure to show all the landmarks indicated in the accompanying diagram, and label all parts of your drawing. c. In 30 percent of meioses, there will be a crossover somewhere in the region…arrow_forwardOrangutans are an endangered species in their natural environment (the islands of Borneo and Sumatra), and so a captive-breeding program has been established using orangutans currently held in zoos throughout the world. One component of this program is research into orangutan cytogenetics. This research has shown that all orangutans from Borneo carry one form of chromosome 2, as shown in the accompanying diagram, and all orangutans from Sumatra carry the other form. Before this cytogenetic difference became known, some matings were carried out between animals from different islands, and 14 hybrid progeny are now being raised in captivity.q3.1 q2.2 q2.1 q1.2 q1.1Borneop1.1 p1.2cenq3.1 q2.2 q2.1 p1.1Sumatrap1.2cenq1.1 q1.2a. What term or terms describe the differences between these chromosomes?b. Draw the chromosomes 2, paired in the first meiotic prophase, of such a hybrid orangutan. Be sure to show all the landmarks indicated in the accompanying diagram, and label all parts of your…arrow_forward
- Human Biology (MindTap Course List)BiologyISBN:9781305112100Author:Cecie Starr, Beverly McMillanPublisher:Cengage Learning