Menkes Kinky Hair Disease ATP7A

A 4-month-old boy is admitted with intractable seizures, profound hypotonia, developmental regression, and sparse, steely-gray, brittle hair with pili torti on microscopy. MRI shows cerebral atrophy and "corkscrew vessels." Serum copper is undetectable (12 µg/dL; normal 70–130) and ceruloplasmin is low (3 mg/dL; normal 20–40). Whole-exome sequencing confirms a hemizygous nonsense variant in ATP7A. A detailed pedigree shows two maternal uncles died in early infancy with similar features, but the mother, maternal aunt, and maternal grandmother are unaffected carriers. There is no father-to-son transmission and no affected females in the family. The inheritance pattern marked **A** in the diagram is demonstrated by this family. Which of the following best describes this pattern?