December 07, 2018
AkraMania
Theme: Trinucleotide repeat disorders
| A. | CTG |
| B. | CGG |
| C. | AAA |
| D. | CAG |
| E. | CAC |
| F. | GAU |
| G. | GAA |
| H. | UAG |
| I. | AGU |
| J. | UGA |
Select the trinucleotide involved in each of the following disorders
| NaN. | Huntington's disease |
| CAG 85%
|
| NaN. | Fragile X syndrome |
| CGG 81%
|
| NaN. | Friedreich's ataxia |
| GAA 49%
|
Trinucleotide repeat disorders
Trinucleotide repeat disorders are caused by the abnormal presence of an expanded sequence of trinucleotide repeats.
The hallmark of these disorders is the concept of anticipation. This refers to the amplification of the number of repeats over successive generations. This results in an earlier age of onset and often a more sever form of the condition.
The following table lists the trinucleotide repeat disorders and illustrates the repeats considered to give rise to the condition:
| Condition | Repeat sequence involved |
|---|
| Fragile X syndrome | CGG |
| Myotonic dystrophy | CTG |
| Huntington's disease | CAG |
| Friedreich's ataxia | GAA |
| Spinocerebellar ataxia | CAG |
The mutations seen in trinucleotide repeat disorders are referred to as 'dynamic'.
