How many defective copies of a gene must someone inherit to

How many defective copies of a gene must someone inherit to express a disease caused by a dominant gene? How many defective copies of a gene must someone inherit to express a recessive disorder? What is the expected phenotypic ratio of affected to unaffected individuals for a dominant disorder?

Solution

In autosomal dominant inheritance even single copy of gene requires to get expressed phenotypically in offspring

In autosomal recessive inheritance two copies of allele of the disease are require for an individual to the susceptible to express phenotypically

There is 50% chances of offspring to get affected in a dominant disorder