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.Which one of the following best describes the cause of this genetic abnormality?: (A) Trisomy, (B) Monosomy, (C) Trinucleotide repeat, (D) Translocation
Answer is B. This patient has Turner syndrome or 45 XO. She is missing a second sex (X) chromosome. She would not have a Barr body and would be infertile. She is phenotypically female.