The mutant allele for Huntington disease, and the ones for several other disease
ID: 53505 • Letter: T
Question
The mutant allele for Huntington disease, and the ones for several other diseases since, was cloned and sequenced. Comparisons of the mutant and WT sequences revealed the difference to be:
a single nucleotide difference (point mutation).
a translocation that fused two genes in an inappropriate fashion.
a deletion in an important regulatory region for the affected gene.
an increase in the number of repeats of a trinucleotide sequence.
None at the sequence level, leading to the discovery of epigenetics.
Explanation / Answer
The option correct option is Option d.
The mutant allele for Huntington disease, and the ones for several other diseases since, was cloned and sequenced. Comparisons of the mutant and WT sequences revealed the difference to be:an increase in the number of repeats of a trinucleotide sequence.
Huntington's disease (HD) is a fatal neurodegenerative disorder with an autosomal dominant mode of inheritance. It leads to progressive dementia, psychiatric symptoms and an incapacitating choreiform movement disorder, culminating in premature death.
HD is caused by an increased CAG repeat number in a gene coding for a protein with unknown function, called huntingtin. The trinucleotide CAG codes for the amino acid glutamine and the expanded CAG repeats are translated into a series of uninterrupted glutamine residues.The CAG repeat is unstable and changes size during transmission from one generation to the next.