Question

Part B Determining genotypes in pedigrees of X-linked conditions

The pedigree from Part A is shown below. Fill in the most likely genotypes of the indicated individuals in the pedigree. Note that a dominant allele followed by an underscore (_) indicates that either the dominant or the recessive allele may be present at the second position. Drag one pink label (for condition A, autosomal recessive) to each pink target. Drag one blue label (for condition B, X-linked recessive) to each blue target. Labels can be used once, more than once, or not at all.

In this tutorial, you will use pedigrees to explore the differences between X-linked and autosomal inheritance patterns. You are investigating the inheritance of two rare conditions (A and B) in an extended family of thoroughbred racehorses. You have constructed the following pedigree for these conditions. Identify the inheritance mode of each condition by using the labels to complete the table. Labels can be used once, more than once, or not at all. ANSWER: View Correct Begin a pedigree analysis by determining the inheritance mode of the condition. Is the condition recessive or dominant? Dominant conditions require that an affected individual have at least one affected parent. An affected offspring of two unaffected parents indicates a recessive condition. (This is the case for both conditions A and B.) Is the condition autosomal or X-linked? An affected female offspring of two unaffected parents indicates an autosomal recessive condition. (This is the case for condition A.) If the condition were X-linked, the male parent would be affected. To distinguish between rare X-linked and autosomal recessive conditions, choose the simpler mode for the observed pattern-that is, the mode that requires fewer unrelated individuals to carry a rare allele. In this example, the autosomal recessive mode would require two unrelated horses (11-1 and II-5) to carry a rare recessive allele for condition B, whereas the X-linked recessive mode requires only one. Therefore, the X-linked recessive mode is a better choice for condition B. Part B Determining genotypes in pedigrees of X-linked conditions The pedigree from Part A is shown below. Fill in the most likely genotypes of the indicated individuals in the pedigree. Note that a dominant allele followed by an underscore (_) indicates that either the dominant or the recessive allele may be present at the second position. Drag one pink label (for condition A, autosomal recessive) to each pink target. Drag one blue label (for condition B, X-linked recessive) to each blue target. Labels can be used once, more than once, or not at all.

Answer 1

A XBY A XBY AA XBXB AA XBXb A XBX A XBY IV Condition A O condition B