Question

Huntington’s disease is an autosomal dominant inherited disease. People who inherit this disease develop jerky muscle movements, slurred speech, and behavioral and judgment difficulties. A person with Huntington’s disease does not develop symptoms until they are 30 to 50 years of age. Below is a pedigree of a family impacted by Huntington’s Disease.



Individual 12 wants to have children and his partner does not have Huntington’s disease. Based on the reading and pedigree, to what extent should individual 12 be concerned about passing this genetic disease to his offspring?

His future children will most likely be impacted because his parents, individuals 7 and 8, have Huntington’s Disease.

Because individuals 13 and 14 are affected siblings, individual 12 likely inherited the dominant allele and has a high chance of passing it to his offspring.

Since individual 12 is homozygous recessive, he would not have to worry about passing the genetic disorder to his children.

Individual 12 is a possible carrier and should be concerned about passing this trait to his children

Answer 1

Best answer: "Individual 12 is a possible carrier and should be concerned about passing this trait to his children."

Why: Huntington disease is autosomal dominant and typically caused by a single mutant allele. Because symptoms often appear only at 30–50 years, an apparently unaffected person can still carry the mutant allele (presymptomatic). If individual 12 does carry one mutant allele, each child with an unaffected partner has a 50% chance of inheriting it. The presence of affected siblings (13 and 14) or affected parents increases that he is at risk but does not prove he has the allele — each sibling independently has a ~50% risk (assuming affected parent(s) are heterozygous).

Practical next steps: genetic counseling and predictive genetic testing if he wants a definite answer; discuss reproductive options (prenatal testing, preimplantation genetic diagnosis, donor gametes) and psychosocial/insurance implications.