Dr. Thomas has found that William, her patient, has a defect in a gene on the X chromosome of his 23rd pair, which has resulted in a deficiency of a protein needed for William's brain development. William most likely suffers from
A) Down syndrome.
B) cretinism.
C) fragile X syndrome.
D) fetal alcohol syndrome.

Question

Quizplus · Accepted Answer

Fragile X syndrome is caused by a defect in the FMR1 gene on the X chromosome, leading to a deficiency in the protein FMRP, which is needed for brain development. Down syndrome is caused by a trisomy of chromosome 21, cretinism is caused by iodine deficiency during fetal development, and fetal alcohol syndrome is caused by maternal alcohol consumption during pregnancy. None of these conditions are related to a deficiency in a protein needed for brain development due to a defect in a gene on the X chromosome.

Dr Thomas Has Found That William, Her Patient, Has a Defect