A DNA variant has been found linked to a rare autosomal dominant disease in humans and can thus beused as a marker to follow inheritance of the diseaseallele. In an informative family (in which one parentis heterozygous for both the disease allele and the DNA marker in a known chromosomal arrangementof alleles, and his or her mate does not have the samealleles of the DNA variant), the reliability of such amarker as a predictor of the disease in a fetus is related to the map distance between the DNA markerand the gene causing the disease.Imagine that a man affected with the disease(genotype Dd) is heterozygous for the V1and V2forms of the DNA variant, with form V1on the samechromosome as the D allele and form V2on the samechromosome as d. His wife is V3V3dd, where V3isanother allele of the DNA marker. Typing of the fetusby amniocentesis reveals that the fetus has the V2andV3variants of the DNA marker. How likely is it thatthe fetus has inherited the disease allele D if thedistance measured in a two-point cross between theD locus and the marker locus is (a) 0 m.u., (b) 1 m.u.,(c) 5 m.u., (d) 10 m.u., (e) 50 m.u.?
A DNA variant has been found linked to a rare autosomal dominant disease in humans and can thus be
used as a marker to follow inheritance of the disease
allele. In an informative family (in which one parent
is heterozygous for both the disease allele and the DNA marker in a known chromosomal arrangement
of alleles, and his or her mate does not have the same
alleles of the DNA variant), the reliability of such a
marker as a predictor of the disease in a fetus is related to the map distance between the DNA marker
and the gene causing the disease.
Imagine that a man affected with the disease
(genotype Dd) is heterozygous for the V1
and V2
forms of the DNA variant, with form V1
on the same
chromosome as the D allele and form V2
on the same
chromosome as d. His wife is V3
V3
dd, where V3
is
another allele of the DNA marker. Typing of the fetus
by amniocentesis reveals that the fetus has the V2
and
V3
variants of the DNA marker. How likely is it that
the fetus has inherited the disease allele D if the
distance measured in a two-point cross between the
D locus and the marker locus is (a) 0 m.u., (b) 1 m.u.,
(c) 5 m.u., (d) 10 m.u., (e) 50 m.u.?
Trending now
This is a popular solution!
Step by step
Solved in 2 steps
