Hereditary diseases are represented by A and A: because they are dominant inheritance, both Aa and AA may get sick.

The dominant incidence was 19%(AA+Aa), and the recessive AA was 81%. From this equation, we can know that the genetic probability of A = 9/ 100 is 9/ 10. It can be inferred that the probability of AA is10% *10% =1%; The probability of Aa is 100%-AA-aa= 18%.

Genotypes aa =10% *10% =1%,aa=90%*90%=8 1%, Aa= 18%.

There may be two genotypes Aa and AA when the wife is sick. Since the incidence of the disease is 19%, the disease probability is divided by 19%:

The dominant probability of AA =1%19%, that is,119; The dominance probability of Aa =18%19%, that is, 18/ 19. Because it is a dominant inheritance, the wife has two genotypes:

(1) If the wife is aa (119) and the husband is normal AA, then the disease probability of offspring =119;

(2) If the wife is Aa( 18/ 19) and the husband is normal Aa, then the disease probability of the offspring is 9/ 19.

Then the disease probability of offspring p =119+9/19 =10/19.