Final answer:
Turner's syndrome in a patient is most likely caused by nondisjunction of the X chromosome, leading to a single X chromosome in the affected female (monosomy X).
Step-by-step explanation:
The genetic event that could have caused Turner's syndrome in patient 367 is most likely A) Nondisjunction of the X chromosome. Turner syndrome is characterized by the presence of only one copy of the X chromosome, which is described as a 45,X karyotype or monosomy X. This occurs when the X chromosome fails to separate during the formation of reproductive cells, a process known as nondisjunction, and results in an egg or sperm with an abnormal number of chromosomes. Following fertilization, if an egg with no X chromosome is fertilized by a sperm carrying an X chromosome, or if a normal egg is fertilized by a sperm with no sex chromosome, the resulting zygote will have the Turner syndrome genotype. Other options such as B) Nondisjunction of the Y chromosome, C) Deletion of the X chromosome, and D) Duplication of the X chromosome lead to different conditions and would not result in Turner syndrome.