A 20-year-old female presents for an infertility workup. She has never had a menstrual period. She is short with a broad chest, webbed neck, and low-set ears. It is demonstrated that she has an abnormal karyotype.The cause of the woman's abnormal karyotype is which one of the following?
Maternal nondisjunction
Paternal nondisjunction
Both maternal and paternal nondisjunction
Either maternal or paternal nondisjunction
Monosomy X (Turner syndrome) can be as a result of either maternal nondisjunction (an egg is created lacking an X chromosome, whereas another egg has two X chromosomes) or paternal nondisjunction (a sperm lacks the X chromosome, whereas another sperm contains both the X and Y chromosomes). Turner syndrome is not caused by translocation events, either reciprocal or Robertsonian (recall that Robertsonian translocations only occur among acrocentric chromosomes, and the X chromosome if not acrocentric).
Molecular Genetics