Question

Suppose in a hospital in the United Kingdom, out of 100,986 of babies born in the last 20 years, 15 children were born with myotonic dystrophy. Myotonic dystrophy is caused by an autosomal dominant mutation in the dystrophia myotonica protein kinase gene, DMPK. Myotonic dystrophy causes progressive muscle weakness, cataracts, and difficulty relaxing clenched hands. Of the 15 affected children, only 3 were born to a parent with a DMPK mutation. Given this information, what is the mutation rate of the DMPK gene?

Answer 1

Answer:

$20$ percent

Explanation:

Dystrophia myotonica protein kinase gene, DMPK is a kind of autosomal dominant mutation. Since this disease is autosomal, it is not affected by the sex chromosome. Out of total 23 chromosome pairs in human being, 22 are autosomal chromosome while one pair is sex chromosome. Also autosomal dominant means that the mutated gene is a dominant gene that is found in the non sex chromosomes.

Thus, only one mutated allele is required to pass on the mutation through the families hierarchy.

Thus, the mutation rate of the DMPK gene is

$\frac{3}{15} * 100\\= \frac{1}{5} * 100\\= 20$%

Answer 2

Answer:

0.00000594/year

Explanation:

Among 100986 babies, 15 are born with myogenic dystrophy.Among these 15 babies, 3 are born with DMPK mutation.

So,in 12 babies the myogenic dystrophy comes through mutation.

So,the rate of mutation is,

{12/(100986*20)}=0.00000594/year