You suspect that a serious developmental disorder is due to a chromosome abnormality and prepare a karyotype from an affected individual. In analyzing the karyotype, how could you distinguish trisomy from a chromosome structural defect such as a duplication?
A) In trisomy there would be one extra chromosome; in a duplication, one chromosome would have two copies of a portion of the chromosome.
B) The chromosome number in both cases would be normal, but in trisomy there would be three chromatids on one chromosome and in a duplication there would be two chromatids on one chromosome.
C) In both cases there would be an extra chromosome, but in trisomy there would be three chromatids on one chromosome and in a duplication there would be two chromatids on one chromosome.
D) The chromosome number in trisomy would be normal; in a duplication, there would be one more chromosome.
Answer: A