What is the best explanation for a person whose karyotype from blood cells shows nearly all cells to have trisomy 21 to have 10 clinical manifestations of Downsyndromeand an above-average intelligence?
A)The trisomy was a result of nondisjunction of paternal gametes instead of maternal gametes.
B)The person has pseudo-Down syndrome, in which environmental conditions caused the person to have development that mimics only the physical manifestations.
C)The person has genomic imprinting, in which the paternal number 21 chromosome is not expressed, and both maternally derived number 21 chromosomes are expressed.
D)The person has mosaicism of trisomy 21, with blood cells having a high proportion and neurons having a low proportion of cells, with three number 21 chromosomes.

Question

Quizplus · Accepted Answer

Mosaicism is a condition in which two (or more) different karyotypes are consistently present in one individual. This represents that some cells have an abnormal karyotype, and others have a normal karyotype. Mosaicism can be tissue specific, meaning that some tissues can express a mixture of normal and abnormal karyotypes, and other tissues may express all or nearly all of just one type. In this case, the most likely explanation is that the person has far fewer neurons with trisomy 21.

What Is the Best Explanation for a Person Whose Karyotype