The genetic abnormality at chromosome Xq27.3 is most closely associated with which condition?

Prepare for the American Board of Professional Psychology (ABPP) Exam with flashcards and multiple-choice questions. Each question includes insights and explanations to help you excel. Get ready for your certification journey!

Multiple Choice

The genetic abnormality at chromosome Xq27.3 is most closely associated with which condition?

Fragile X syndrome comes from an expansion of CGG repeats in the FMR1 gene located on the X chromosome at Xq27.3. When the repeats exceed about 200, the gene becomes methylated and silenced, eliminating the FMRP protein needed for normal neural development. This X-linked change at Xq27.3 explains the characteristic cognitive and behavioral features of Fragile X, such as intellectual disability and autism spectrum traits, with macroorchidism commonly seen in males after puberty. Other options reflect different genetic mechanisms: Klinefelter involves an extra X chromosome (XXY) and isn’t linked to Xq27.3; Prader-Willi results from a deletion or uniparental disomy on chromosome 15; Phenylketonuria is due to PAH gene mutations on chromosome 12.

Fragile X syndrome comes from an expansion of CGG repeats in the FMR1 gene located on the X chromosome at Xq27.3. When the repeats exceed about 200, the gene becomes methylated and silenced, eliminating the FMRP protein needed for normal neural development. This X-linked change at Xq27.3 explains the characteristic cognitive and behavioral features of Fragile X, such as intellectual disability and autism spectrum traits, with macroorchidism commonly seen in males after puberty. Other options reflect different genetic mechanisms: Klinefelter involves an extra X chromosome (XXY) and isn’t linked to Xq27.3; Prader-Willi results from a deletion or uniparental disomy on chromosome 15; Phenylketonuria is due to PAH gene mutations on chromosome 12.

More practice questions