Which term best describes trinucleotide repeat diseases?

Which term best describes trinucleotide repeat diseases?

• A. Autosomal dominant disease
• B. X-linked disorders
• C. Hemophilia
• D. Trinucleotide repeat diseases

Answer: (D)

Trinucleotide repeat diseases are defined by expansions of three-nucleotide sequences in specific genes, which disrupt gene function and lead to disease through RNA toxicity or abnormal protein production, depending on where the repeat is. This mutational mechanism is the unifying feature of the group, so the best descriptor is the category itself: trinucleotide repeat diseases. For context, Huntington disease results from CAG repeat expansions in HTT and is autosomal dominant; fragile X syndrome comes from CGG repeats in FMR1 and is X-linked; myotonic dystrophy type 1 stems from CTG repeats and is autosomal dominant. These examples show that inheritance patterns vary, but the common thread is the repeat expansion causing disease.

Trinucleotide repeat diseases are defined by expansions of three-nucleotide sequences in specific genes, which disrupt gene function and lead to disease through RNA toxicity or abnormal protein production, depending on where the repeat is. This mutational mechanism is the unifying feature of the group, so the best descriptor is the category itself: trinucleotide repeat diseases. For context, Huntington disease results from CAG repeat expansions in HTT and is autosomal dominant; fragile X syndrome comes from CGG repeats in FMR1 and is X-linked; myotonic dystrophy type 1 stems from CTG repeats and is autosomal dominant. These examples show that inheritance patterns vary, but the common thread is the repeat expansion causing disease.