Chromosomal Disorders Practice Test

A 2-day-old newborn with trisomy 21 is evaluated for gastrointestinal obstruction. Abdominal radiograph shows a “double bubble” sign. Which congenital anomaly best explains this imaging finding in this chromosomal disorder?

A 1-month-old infant has a high-pitched cry, microcephaly, and hypotonia. Karyotype shows 46,XY,del(5)(p15). The parents ask what type of chromosomal change this represents compared with trisomy 21. Which statement best explains the difference?