Q. Hutchinson-Gilford progeria is an exceedingly rare human genetic disorder in which there is very early senility, and death, usually of coronary artery disease, at an average age of approximately 13. Patients, who look very old even as children, do not live to reproduce. Which of the next represents the most likely assumption?

Each patient will have had as a minimum one affected family member in a previous generation.

Successive generations of a family will continue to have more and more cases over time.

The disorder might be due to mutation in a single protein-coding gene.

The disease is autosomal dominant.

All cases should occur in relatives; therefore, there must be only one mutant allele.