Select a Community
Are you sure you want to trigger topic in your Anconeus AI algorithm?
You are done for today with this topic.
Would you like to start learning session with this topic items scheduled for future?
CGG
30%
3/10
GAA
0%
0/10
CAG
CTG
40%
4/10
GCC
Select Answer to see Preferred Response
Fragile X syndrome is a trinucleotide repeat expansion disease caused by CGG repeats in the FMR1 gene on the X chromosome. Fragile X syndrome is the second most common cause of genetic mental retardation after Down syndrome. It is caused by CGG trinucleotide repeat expansion affecting the methylation and expression of the FMR1 gene on the X chromosome. It causes the stereotypical findings of macroorchidism (enlarged testes), elongated face, large jaw, large everted ears, autism, and mitral valve prolapse. Additionally, most affected males have mild to severe mental retardation. Currently, prenatal testing with chorionic villus sampling or amniocentesis allows accurate diagnosis in those at risk for fragile x syndrome. Wattendorf and Muenke review the diagnosis of Fragile X syndrome. They state that because the typical characteristics are subtle during early childhood, the average age of diagnosis is 8 years old. Typically, the initial finding is delayed attainment of developmental milestones. Diagnosis is confirmed with molecular genetic testing of the FMR1 gene. Hall et al. examined longitudinal changes in intellectual development in children with Fragile X syndrome by comparing 145 children with Fragile X syndrome to their matched siblings. Compared to their unaffected siblings, children with fragile X syndrome obtained significantly lower percentage scores on all intelligence tests at all time points. During the time between the first and second assessments, the annual rate of intellectual development was approximately 2.2 times faster in the unaffected children compared to the children with fragile X. Image A displays the classic findings of Fragile X, including an elongated face, large jaw, and large everted ears. Incorrect Answers: Answer 2: The GAA trinucleotide repeat is observed in Friedreich's ataxia. Answer 3: The CAG trinucleotide repeat is observed in Huntington's disease. Answer 4: The CTG trinucleotide repeat is observed in Myotonic dystrophy. Answer 5: The GCC trinucleotide repeat is not a characteristic repeat seen in the trinucleotide repeat expansion diseases.
3.4
(8)
Please Login to add comment