A couple has a child with neurofibromatosis. They come to your genetic counseling office for help. After taking an extensive family history, you determine that there is no history of this disease on either side of the family. The couple wants to have another child and wants to be advised about the risks of that child having neurofibromatosis. What advice do you give them?

Huntington disease (HD) is a genetic disorder that usually first appears in middle age and, over time, leads to involuntary movements, impaired speech, difficulty swallowing and speaking, and cognitive decline. There is no cure for HD, and affected individuals eventually die, usually after 10 to 15 years of progressively worsening symptoms. Huntington disease is inherited as an autosomal dominant disorder. Presymptomatic genetic testing for HD is available for people with a family history of the disease. Individuals who have a parent with HD have a 50% chance of inheriting the HD gene and eventually having HD. Some of these individuals want to know if they will eventually get the disease, and they undergo presymptomatic genetic testing. Others do not want to know, given that there is no cure or effective treatment for the disease. If you were at risk for HD, would you want to undergo genetic testing? What are some reasons for and against having a genetic test for HD?

As a genetic counselor, you inform Susan and John that a blood test for cystic fibrosis is available. Would you recommend genetic testing for Susan and John? Explain.

Explain the following diagram. It refers to a pedigree on the disease called phenylketonuria. Briefly explain about the disease; specifically biochemical and genetic aspects. Then I interpret the pedigree. Say what type of inheritance the condition exhibits