Final answer:
Huntington's disease is a genetic disorder caused by a mutation in the huntingtin protein gene, leading to neuron degeneration and resulting in behavioral and cognitive symptoms, with a 50% chance of passing the dominant allele to offspring. There is no cure, but symptoms are managed to improve quality of life.
Step-by-step explanation:
Huntington's disease is a neurodegenerative genetic disorder caused by a mutation in the gene that encodes for the huntingtin protein. This mutation leads to the production of a protein with an abnormally long sequence of glutamine residues which causes the degeneration of neurons, particularly those in the cortical and striatal regions of the brain. Those who inherit the dominant Huntington allele (Hh), are certain to develop the disease, typically showing symptoms around middle age. Behavioral changes due to Huntington's disease can include muscle spasms and personality shifts. Cognitive decline and difficulty with voluntary movement are also common as the disease progresses. A hallmark sign of Huntington's is involuntary spastic movement. The loss of specific GABA-releasing neurons in the brain, known as GABAergic medium-sized spiny neurons, is associated with these symptoms. To understand the inheritance pattern of Huntington's disease, a Punnett square can be used to predict a 50 percent chance of passing this autosomal dominant disorder to offspring if one parent has the disease. Unfortunately, there is currently no cure for Huntington's disease, but treatments aim to manage symptoms and improve quality of life.