A 45-year-old man comes to the physician because of involuntary movements and behavioral disturbance. He has frequent, jerky, irregular movements of his upper extremities that have progressively worsened over the past month. His family and friends also say that he has become increasingly irritable over the past year. Genetic testing shows a mutation affecting the huntingtin protein that causes transcriptional repression of a number of other genes. Which of the following mechanisms is most likely responsible for the decreased gene expression seen in this patient?

Question

A 45-year-old man comes to the physician because of involuntary movements and behavioral disturbance.  He has frequent, jerky, irregular movements of his upper extremities that have progressively worsened over the past month.  His family and friends also say that he has become increasingly irritable over the past year.  Genetic testing shows a mutation affecting the huntingtin protein that causes transcriptional repression of a number of other genes.  Which of the following mechanisms is most likely responsible for the decreased gene expression seen in this patient?

Quizplus · Accepted Answer

Eductional Objective: Hypo-acetylated histones bind tightly to DNA and prevent transcription of genes in their associated regions.  Alteration of gene expression in Huntington disease occurs in part due to deacetylation of histones.  This prevents the transcription of certain genes that code for neurotrophic factors, contributing to neuronal cell death.

A 45-Year-Old Man Comes to the Physician Because of Involuntary