Pediatrics Board Review Sample Questions

The correct answer is B. Prader-Willi syndrome

Explanation: There are various causes of intellectual disability. Prader-Willi syndrome is a genetic disorder characterized by infantile hypotonia, short stature, dysmorphic facies including a wide mouth, small feet, developmental delay, hypogonadism, hyperphagia, and obesity. Infants feed poorly but then become hyperphagic when older. Another disorder associated with developmental delay and obesity is Laurence-Moon syndrome. Angelman syndrome is a genetically related disorder characterized by intellectual disability, microcephaly, intractable epilepsy, ataxia, inappropriate laughter with a wide-based stance and flailing of the arms at the sides during ambulation (hence the name happy puppet syndrome), prominent jaw with a thin upper lip, and impaired speech development. Another genetic disorder associated with developmental delay and a happy affect William syndrome, which is associated with congenital heart disease. Prader-Willi and Angelman syndrome both result from a microdeletion on chromosome 15q11-q13. The same mutation leads to Prader-Willi syndrome when it is paternally inherited and to Angelman syndrome when it is maternally inherited, so-called imprinting. Cri-du-chat syndrome is characterized by an abnormal, cat-like cry, intellectual disability, presence of epicanthal folds, hypertelorism (in which the eyes are farther apart than normal), micrognathia, and other features. It is caused by a deletion on chromosome 5p.