An 8-year-old boy is brought to his pediatrician by his mother because she was
concerned that he was having language-speech problems, was hyperactive,
and was told by teachers that he may have mental retardation. The mother
reports a strong family history of mental retardation in males. The boy on
exam is found to have a large jaw, prominent ears, and enlarged testes
(macroorchidism). The mother was told her family had a genetic problem
causing the mental retardation. The patient underwent a series of blood tests
and was scheduled to see a genetic counselor, who expressed that the etiology
of the genetic defect was likely transmitted from his mother. The genetic coun-
selor states that his mother likely has a silent mutation.
What is the most likely diagnosis?
Which chromosome is likely to be affected?
What are some types of biochemical mutations?
What is the biochemical basis of the different types of mutations?