Huntington Chorea is a serious genetic disorder caused by a rare dominant allele (H) at an autosomal locus on chromosome 4. Individuals bearing an H allele produce a damaging protein that accumulates within the brain, leading to progressive loss of motor control and often to dementia. The disease often manifests itself later in life, and usually, Huntington Chorea victims die within 15 years after their neurological symptoms are diagnosed, but some people die before even being diagnosed. In some rural Michigan populations, the frequency of people diagnosed with the disorder is unusually high, about 0.05%. Genetic work shows that the wild-type allele (+) mutates into H at a rate of 9.56x10-7 mutations per gamete.
Use these data to estimate how many children out of 10,000,000 births to parents without the disorder will have Huntington’s Chorea and if these Michigan populations are at mutation-selection equilibrium, estimate the relative fitness of individuals possessing this genetic disorder (express your answer with at least 4 digits after the decimal point). Assume that homozygotes for the H allele are non-existent because the H allele is super rare, and all individuals with Huntington Chorea are heterozygotes, H+.
Huntington's Chorea is an inherited disorder that affects the nervous system.
It is caused by a dominant allele. This means that it can be passed on by just one parent if they have disorder.
H+H+ - allele for the disorder
HH - allele for normal gene
If they are crossed, three normal gametes and one disordered gamete is produced.
Since, per normal gamete, 9. 56 x 10-7 mutations are caused.
Therefore, 3 gametes would result in (3 x 9.56 x 10-7) mutations, which is equal to
0.2868x10-5 mutations out of 4 birth.
Therefore, out of 10,000,000 births, children with Huntington' Chorea disease are 10, 000, 000 x 0.2868 x 10-5 /4 = 7.1700
Get Answers For Free
Most questions answered within 1 hours.