Problem:
A male infant who appeared normal at birth began to develop lethargy, hypothermia and apnea at 42 hours after delivery. It was determined he had a deficiency in ornithine transcarbamoylase.
A deficiency in ornithine transcarbamoylase is an X-linked heritable disorder; although neither parent has ever presented with symptoms.
In order for this male infant to present with symptoms, which of the following must be true with regards to his parents? Please explain it .