Question

Which of the following genetic disorders is/are caused by trinucleotide repeat expansions?

• A. Huntington’s disease
• B. \(\beta\)-thalassemia
• C. Fragile X syndrome
• D. Cystic fibrosis

Hint:

Trinucleotide repeat disorders often exhibit anticipation, where the severity increases and the age of onset decreases in successive generations.

Answer 1

The Correct Option is A, C

Trinucleotide repeat expansion disorders are a class of genetic conditions caused by the abnormal repetition of three-nucleotide sequences (e.g., CAG, CGG) in certain genes. These expansions disrupt gene function or expression, leading to various diseases.
Option (A): Huntington’s disease is caused by CAG trinucleotide repeat expansion in the HTT gene. (Correct)
Option (B): \(\beta\)-thalassemia results from mutations affecting the beta-globin gene, but it is not related to trinucleotide repeat expansions. (Incorrect)
Option (C): Fragile X syndrome is caused by CGG repeat expansion in the FMR1 gene. (Correct)
Option (D): Cystic fibrosis is caused by mutations in the CFTR gene, most commonly a 3-base deletion (\( \Delta F508 \)), not a repeat expansion. (Incorrect)
\[ {Therefore, correct options are (A) and (C).} \]