Exercise II - by the HEX-B gene. Mutations in the HEX-B...

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Introduction to Human Genetics 096:116 Application Exercise II Due by midnight on 10/27/06 Name: Tay-Sachs disease is an autosomal recessive condition that results in progressive nervous system degeneration. It is caused by mutations in the HEXA gene, which encodes the alpha subunit of the hexosaminidase enzyme. 1) More than 70 mutations in the HEXA gene have been described. The three HEXA mutations listed below were identified among heterozygotes in a screening program. Briefly describe how each mutation alters the gene product. (3 points) a) A 4-base pair insertion in exon 11 b) A G-to-C transversion at the 5-prime splice site in intron 12 c) A glycine 269-to-serine mutation in exon 7
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2) Some of the single base substitutions described in the HEXA gene do not affect the gene product. Give two possible explanations for this observation. (2 points) 3) Hexosaminidase is a dimeric (two-part) enzyme that also has a beta subunit, encoded
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Unformatted text preview: by the HEX-B gene. Mutations in the HEX-B gene cause Sandhoff disease. How would you expect the symptoms of Sandhoff disease to compare with those of Tay-Sachs disease? Give a reason for your answer. (2 points) 4) Briefly describe why Tay-Sachs disease is classified as: (3 points) a) An inborn error of metabolism. b) A lysosomal storage disease. Impairment of the alpha subunit of HEXA results in the absence of enzyme activity. HEXA is involved in the cleaving the terminal N-acetylgalactoamine or N- acetylglucosamine from glycoconjugates. HEXA is able to transport GM2 ganglioside to the lysosome and cleave its glycosidic bond. A deficit of this enzyme results in the accumulation of GM2 ganglioside in the lysosomes of neurons leading to progressive neuronal degeneration and death at an early age (usually by 2-4 years)....
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This note was uploaded on 04/13/2008 for the course NURSING 96:116 taught by Professor Schutte during the Spring '08 term at University of Iowa.

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Exercise II - by the HEX-B gene. Mutations in the HEX-B...

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