Which syndrome is commonly characterized by macro-orchidism and is inherited in an X-linked manner?

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

Which syndrome is commonly characterized by macro-orchidism and is inherited in an X-linked manner?

Macro-orchidism in affected males and an X-linked pattern of inheritance are hallmarks of Fragile X syndrome. The condition arises from expansion of CGG repeats in the FMR1 gene on the X chromosome, leading to methylation and silencing of the FMRP protein that regulates synaptic plasticity. This genetic change produces intellectual disability, learning difficulties, and often autism spectrum features, with males typically more severely affected. Female carriers may have milder symptoms due to X-inactivation. Other listed syndromes do not feature macro-orchidism or are not X-linked in inheritance, such as Rett syndrome (which involves MECP2 and has characteristic hand-wringing and regression), Williams syndrome (a deletion on chromosome 7), and Angelman syndrome (imprinting on chromosome 15).

Macro-orchidism in affected males and an X-linked pattern of inheritance are hallmarks of Fragile X syndrome. The condition arises from expansion of CGG repeats in the FMR1 gene on the X chromosome, leading to methylation and silencing of the FMRP protein that regulates synaptic plasticity. This genetic change produces intellectual disability, learning difficulties, and often autism spectrum features, with males typically more severely affected. Female carriers may have milder symptoms due to X-inactivation. Other listed syndromes do not feature macro-orchidism or are not X-linked in inheritance, such as Rett syndrome (which involves MECP2 and has characteristic hand-wringing and regression), Williams syndrome (a deletion on chromosome 7), and Angelman syndrome (imprinting on chromosome 15).

More practice questions