The PMHNP is evaluating an 11-year-old boy with intellectual disabilities, a long face, and large ears. He has midface hypoplasia, hyperextensible joints, and a short stature. She explains to the family that the child has which of the following?

Choice A reason: Williams syndrome presents with distinctive “elfin” facial features, cardiovascular anomalies, and overly friendly behavior, not the described features. Choice B reason: Rett syndrome primarily affects girls and involves loss of purposeful hand skills, language regression, and stereotypic hand movements. Choice C reason: Fragile X syndrome is characterized by intellectual disability, long face, large ears, midface hypoplasia, hyperextensible joints, and short stature, matching this patient’s presentation. Choice D reason: Turner syndrome affects females and is characterized by short stature, webbed neck, and gonadal dysgenesis, not the features described.