Question

Age of Onset O N Number of Repeats (R X) O-34 deceased O 39 50 O 35 6 33 R 50 O 38 R 49 O# 35 O 40 O 22 O 18 R- 82 R=57 21 O 16 0 31 From Ramen et al. 1995 Am. J. Hum. Genet. 57:593-602 O:9 R 66 R 58 R 51 R=75 Based on the pedigree above, select all of the conclusions that can be made from the list provided below. In general, with successive As the number of Males are unable to In general, with successive generations, the age of onset for Huntington will decrease Males are unable to pass on the allele for As the number of CAG repeats increased, the age ofHuntington disease to onset decreased their offspring Huntington disease is an autosomal dominant disease meaning only one diseased allele is required for onset. The number of CAG As the number of CAG repeats increased, the age of onset increased. repeats decreased with successive generations The age of onset is earlier in males than in females. Huntington disease is a sex-linked disease, The number of CAG meaning it is carried repeats increased with on the X-chromosome and more common in successive generations. males.

Answer 1

Huntingtons disease condition is inherited in an autosomal dominant pattern, where one copy of the altered gene in each cell is sufficient to cause the disorder. An affected person usually inherits the altered gene from one affected parent.

Conclusions:

HTT disease is autosomal dominant disease

with successive generations the age of onset for disease decreases.

People with the adult-onset form of Huntington disease  have 40 to 50 CAG repeats in the gene, whereas people with the juvenile form of the disorder tend to have more than 60 CAG repeats.

Hence as the number of CAG repeats increased as the age of onset decreased.

CAG repeats increased with successive generation