Question

A 6-year-old boy is brought to the clinic by his mother, who thinks he is "eating too much" because he is gaining weight. She says that as a baby he had hypotonia and a weak cry, and he sta1ted walking at age 2 years. His mother also says he has always been "slower" and shorter than other kids. Which of the following is the most likely cause of the patient's condition?

A. Deletion of q12 on the maternally derived chromosome 15
B. Deletion of q12 on the paternally derived chromosome 15
C. Maternal alcohol use during pregnancy
D. Trinucleotide CAG repeats
E. Trinucleotide CGG repeats

Answer 1

The most likely cause of the boy's symptoms is Prader-Willi syndrome, resulting from a deletion on the paternally derived chromosome 15. It is characterized by developmental delays and excessive eating leading to obesity.

Step-by-step explanation:

The most likely cause of the patient's condition described as a 6-year-old boy with symptoms of hypotonia, a weak cry, late walking, short stature, slower development, and excessive eating leading to weight gain is Prader-Willi syndrome (PWS). This genetic disorder is characterized by a loss of function of genes on chromosome 15, usually related to a lack of genetic material on the paternally derived chromosome. As such, the correct answer is B. Deletion of q12 on the paternally derived chromosome 15. PWS is not commonly inherited but rather occurs due to the genetic changes in the sperm or egg or during embryonic development. Key behavioral criteria for diagnosing PWS from birth to 2 years include a lack of muscle tone and poor sucking behavior, with developmental delays typically being observed between the ages of 6 and 12.