FPGEE for National Association of Boards of Pharmacy (NABP) Practice Exam

What is the genetic condition associated with a missing or partially missing X chromosome in females?

1. Turner syndrome

2. Klinefelter syndrome

3. Down syndrome

4. Fragile X syndrome

The correct answer is: Turner syndrome

Turner syndrome is a genetic condition that occurs when a female is born with a missing or partially missing X chromosome. This results in a total of 45 chromosomes instead of the typical 46. The absence of one of the X chromosomes leads to various physical and developmental characteristics, which can include short stature, delayed puberty, infertility, heart defects, and certain learning difficulties. The other conditions listed involve different chromosomal anomalies and characteristics. Klinefelter syndrome is associated with males having an extra X chromosome, resulting in an XXY configuration. Down syndrome is caused by an extra copy of chromosome 21, leading to intellectual disability and distinct physical features. Fragile X syndrome is linked to a mutation in the FMR1 gene on the X chromosome, leading to developmental delays and cognitive impairments, but does not involve the loss of an X chromosome. Each of these conditions presents unique traits and implications that distinguish them from Turner syndrome.