On prenatal ultrasound, a fetus was noted to be small for gestational age. Cleft lip is present, as are overlapping digits with clinched fists on both hands. Rocker bottom feet are present, along with an atrial septal defect. Genetic analysis is returned showing complete trisomy of chromosome 18. Which of the following is true regarding Trisomy 18?

Correct! Wrong!


The correct answer is C. This condition was described in 1960, by Dr Edwards. It is the second most common autosomal trisomy. Trisomy 21 is the most common. The syndrome occurs in 1:6000 to 1:8000 live births, but 1:2500 pregnancies. This is due to the high rate of pregnancy loss in trisomy 18.