The goal of this assignment is to familiarize you with the process going from the characterization of a disease in human patients, to the identification of a mutated gene causing it, to the use of a mouse model to investigate how this mutation is causing the disease.

Question 1: Based on this video, describe the symptoms of the SCA1 disease.
Answer:
SCA1 is an evolving, neurodegenerative disease involving loss of balance and coordination (a.k.a. ataxia). Moreover, this disease of the nervous system, ultimately leads to severe muscle deterioration, producing unsteady fine motor movement, an unstable gait, laboured breathing, awkward oral communication, difficulty swallowing, with the eventual probability of choking (Howard Hughes Medical Institute …show more content…
Question 2: Explain how to read the chart by indicating what the squares and circles represent and what is the difference between filled and hollow shapes. See image 1 for Family Pedigree Chart.
Answer:
The video & image show basic pedigree symbols as follows: the circle represents a female and the square indicates a male. A filled in shape designates an affected individual with the genetic trait being referenced, while a hollow, or clear, shape symbolizes an unaffected individual who does not have the genetic trait. A deceased individual is characterized by a circle or square with a diagonal line through it. Various lines signify relationship, marriage, and offspring. Each layer/row represents a generation (HHMI, 2003).

Image 1: Pedigree Analysis Chart (HHMI, 2003)

Question 3: Discuss what conclusions can be drawn from the pedigree e.g. assuming that the disease is caused by the mutation of one single gene. For each conclusion, make sure to explain how it is supported by the …show more content…
With the higher number of repeats in SCA1, the protein is then called a polyglutamine; it is a protein accumulation. With a short glutamine region, neurons are healthy. Conversely, with longer glutamine sections, neurons are being modified, or mutated, thus changing the shape of the protein so it can no longer communicate appropriately with other proteins. It was also found there is a correlation between the length of the polyglutamine, and earlier onset/severity of disease (HHMI, 2003; Online Mendelian Inheritance in Man® [OMIM],