Student 1. Case StudyI(Chapter 13) A 55 year-old man presented to his primary ca
ID: 302455 • Letter: S
Question
Student 1. Case StudyI(Chapter 13) A 55 year-old man presented to his primary care physician complaining of slurred speech, problems swallowing food, severe mood swings, and difficulty walking a straight line. Although the problems had started several months before, he went to the physician only after he had been stopped by a police officer who suspected him of driving under the influence. Even though the on-site breathalyzer revealed a blood alcohol content of o.o, the man failed tests of sobriety and was arrested. He was not cleared of the charges until toxicology screens on his blood were found to be negative for all drugs of abuse. The man's parents had died in a car accident when they were in their middle 40s. He was an only child and his parents were also only children of their parents. The man was married, and he and his wife had no children. Neurological studies performed on the man yielded abnormal results Infectious causes such as Neisseria meningitis, Treponema pallidum, Toxoplasma gondii, and Human Immunodeficiency Virus were ruled out by appropriate laboratory tests. Additional tests, including PCR for triplet repeat expansions, were performed. o The negative control (normal sample in lane 1) exhibited PCR products containing 28 CAG repeats in the huntingtin gene The positive control amplicons (lane 4) 40 repeats The patient's sample PCR products (lane 6) had more than 81 repeats o o bp M +EcoP15 404 81 repeats 40 repeats i (5) 320 242 190 147 124 110 i(3') M123 45 6 a) What is the interpretation of these results? b) What is are the possible inheritance patterns? c) What are the implications for the patient and family members?Explanation / Answer
a) the results show that the patient has a mutation which resulted in increased number of triple repeats.
b) the possible inheritance is an autosomal recessive one. This is so because no one in the family has been diagnosed with it. Hence they might be carriers of the condition.
c)implications : if the man's wife were a carrier for the condition, their children have a very high probability of being affected.