What prenatal ultrasound finding is a clue that the fetus may have Down syndrome?
What is the most common event that causes Down syndrome: meiotic nondisjunction, mosaicism, or Robertsonian translocation?
What gene is affected in Fragile X syndrome?
What are the clinical features of Fragile X syndrome?
• Elongated face
• Large jaw
• Large everted ears
• Mitral valve prolapse
What are the clinical features of WIlliams syndrome?
• "Elfin" facies (Will Ferrell was in the movie elf)
• Mental retardation
• Well developed verbal skills
• Extreme friendliness with strangers
• Cardiovascular problems (valvular defects)
What are the possible defects in cases of chromosome 22q11 deletion?
• Cleft palate
• Abnormal facies
• Thymic aplasia
• Cardiac defects
What are the distinguishing characteristics of Klinefelter syndrome compared to Turner syndrome?
• Very tall
• Long extremities
• Testicular atrophy
• Male (XXY)
• Short stature
• Webbed neck
• Shield chest
• Females (XO)