When discussing linkage studies, the instructor mentions that colorblindness is found in a small section of the X chromosome and has been linked to development of which of the following diseases? Select all that apply

Question

A) Early-onset Alzheimer disease
B) Hemophilia A
C) Adrenal hyperplasia
D) Down syndrome

Answer 1

Ans: B, C
Feedback:
When two inherited traits occur together at a rate greater than would occur by chance alone, they are said to be linked. Color blindness has been linked to classic hemophilia A (i.e., lack of factor VIII) in some pedigrees; hemophilia A has been linked to glucose-6-phosphate dehydrogenase deficiency in others; and color blindness has been linked to glucose-6-phosphate dehydrogenase deficiency in still others. Because the gene for color blindness is found on the X chromosome, all three genes must be found in a small section of the X chromosome. Alzheimer disease and Down syndrome have not been associated with a linkage disorder.