Disease X occurs when someone has the xx genotype. However, only 20 of 50 people with the xx genotype actually get the disease. Of the 20 who get disease X, 10 severely display the disease while 10 have a milder form. Explain using the appropriate terms. Solution Answer: XX genotype indicate that it is a autosomal recessively inherited trait and it is female. sickle cell anaemia is one best example which match these results. XhXh = Homozygous dominnant (10 people are severely effected). XXh = heterozygous dominant (10 people may act as carriers) which are milder forms..