12th May 2024

A 6-month-old boy is brought to the clinic for a routine check-up.

A 6-month-old boy is brought to the clinic for a routine check-up. The paediatrician notes hypotonia, a single palmar crease on both hands, and distinctive facial features including a flat facial profile, upward slanting eyes, and a small nose. The child was born to a mother who was 38 at the time of delivery. A karyotype confirms the paediatrician’s suspicion.

Which chromosomal abnormality is most likely to cause his clinical presentation?