Shown below is the pedigree of a rare neurodegenerative diseasein humans.
a. Based on the pedigree, characterize each of the following modes ofinheritance as likely, unlikely, or impossible: autosomal dominant,autosomal recessive, Y linked, X-linked dominant, and X-linkedrecessive. Justify your reasoning.
Further scrutiny of members of this family reveals thefollowing: 1) The diseaseâs degree of expression varies amongindividuals, with some mildly affected, others moderately affectedand still others severely affected; and 2) Individual III-14 waspreviously married. Her ex-husband is phenotypically normal, withno history of the disease in his family going back tengenerations. He has custody of the coupleâs two children, a girland a boy, both of whom are affected with the disease. The partialpedigree is shown below (the âslashâ represents separation ordivorce)
b. Do these findings eliminate any of the remaining âlikely orunlikelyâ modes of inheritance listed in part (a)?Are any of these modes of inheritance still possible? If so, whichone(s) and why?
c. Is mitochondrial inheritance a likely, unlikely or an impossiblemode of inheritance for this disease? Does it provide anexplanation for the diseaseâs variable expressivity?
d. How can mitochondrial inheritance explain individual III-14?
Shown below is the pedigree of a rare neurodegenerative diseasein humans.
a. Based on the pedigree, characterize each of the following modes ofinheritance as likely, unlikely, or impossible: autosomal dominant,autosomal recessive, Y linked, X-linked dominant, and X-linkedrecessive. Justify your reasoning.
Further scrutiny of members of this family reveals thefollowing: 1) The diseaseâs degree of expression varies amongindividuals, with some mildly affected, others moderately affectedand still others severely affected; and 2) Individual III-14 waspreviously married. Her ex-husband is phenotypically normal, withno history of the disease in his family going back tengenerations. He has custody of the coupleâs two children, a girland a boy, both of whom are affected with the disease. The partialpedigree is shown below (the âslashâ represents separation ordivorce)
b. Do these findings eliminate any of the remaining âlikely orunlikelyâ modes of inheritance listed in part (a)?Are any of these modes of inheritance still possible? If so, whichone(s) and why?
c. Is mitochondrial inheritance a likely, unlikely or an impossiblemode of inheritance for this disease? Does it provide anexplanation for the diseaseâs variable expressivity?
d. How can mitochondrial inheritance explain individual III-14?
