Case Study 1: X-Linked Agammagloblinemia 1. Fig 1.5 shows Bill's family tree. It can be seen that only males are affected and that the females who carry the defect (Bill's mother and maternal grandmother) are normal. This inheritance pattern is characteristic of an X-linked recessive trait. We do not know whether Bill's aunts are carriers of the defect because neither of them has had an affective male child. Now that the BTK gene has been mapped, it is possible in principal to detect carriers by testing for the presence of a mutant BTK gene. But there is a much simpler test that was already available at the time of Bill's diagnosis, which is still used routinely. Can you suggest how we could have determined whether Bill's aunts were carriers?
Case Study 1: X-Linked Agammagloblinemia 1. Fig 1.5 shows Bill's family tree. It can be seen that only males are affected and that the females who carry the defect (Bill's mother and maternal grandmother) are normal. This inheritance pattern is characteristic of an X-linked recessive trait. We do not know whether Bill's aunts are carriers of the defect because neither of them has had an affective male child. Now that the BTK gene has been mapped, it is possible in principal to detect carriers by testing for the presence of a mutant BTK gene. But there is a much simpler test that was already available at the time of Bill's diagnosis, which is still used routinely. Can you suggest how we could have determined whether Bill's aunts were carriers?
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| According to the multiplication rule of probability, the chance of crossing two pea plants that are heterozygous for height and have none of four offspring showing the recessive short phenotype is:A. ¼ à ¼ à ¼ à ¼. B. ¾ à ¾ à ¾ à ¾. C. (¼ à ¼ à ¼ à ¼) + (¾ à ¾ à ¾ à ¾). D. ¼ + ¼ + ¼ + ¼. E. None of the above. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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| Females inherit X-linked traits from their maternal parent only. | ||
| Females can inherit a gene for an X-linked trait from either parent. | ||
| Males inherit X-linked traits from their paternal parent only. | ||
| Males can inherit a gene for an X-linked trait from either parent but normally inherit it from their fathers. |
| Males can inherit a gene for an X-linked trait from either parent but normally inherit it from their fathers. |
