The number of CTG repeats in patients with myotonic dystrophy correlates with the clinical phenotype, with higher numbers associated with more severe disease.
Patients with < 40 CTG repeats are considered normal. According to Harper and Johnson, the most common number of repeats in the normal population is 5, with some groups having larger size alleles with 19-30 repeats.
Minimal disease starts to be identified around 50 CTG repeats.
|
|
Posterior Probability for Phenotype |
||
|---|---|---|---|
|
[CTG]n |
Phenotype 1 |
Phenotype 2 |
Phenotype 3 |
|
80 |
1.00 |
0.00 |
0.00 |
|
90 |
1.00 |
0.00 |
0.00 |
|
100 |
0.99 |
0.01 |
0.00 |
|
150 |
0.89 (0.02) |
0.11 (0.02) |
0.00 |
|
200 |
0.44 (0.06) |
0.56 (0.04) |
0.00 |
|
250 |
0.10 (0.01) |
0.90 (0.02) |
0.00 |
|
300 |
0.02 |
0.98 |
0.00 |
|
400 |
0.00 |
0.99 |
0.00 |
|
500 |
0.00 |
0.97 |
0.03 (0.01) |
|
600 |
0.00 |
0.89 (0.01) |
0.11 (0.02) |
|
700 |
0.00 |
0.74 (0.01) |
0.26 (0.04) |
|
800 |
0.00 |
0.55 (0.01) |
0.45 (0.05) |
|
900 |
0.00 |
0.38 (0.01) |
0.62 (0.05) |
|
1,000 |
0.00 |
0.26 (0.01) |
0.74 (0.04) |
|
1,100 |
0.00 |
0.18 (0.01) |
0.82 (0.03) |
|
1,200 |
0.00 |
0.13 (0.01) |
0.87 (0.02) |
|
1,300 |
0.00 |
0.10 (0.01) |
0.90 (0.02) |
|
1,400 |
0.00 |
0.08 (0.01) |
0.92 (0.01) |
|
1,500 |
0.00 |
0.06 (0.01) |
0.94 (0.01) |
|
1,600 |
0.00 |
0.05 (0.01) |
0.95 (0.01) |
|
1,800 |
0.00 |
0.04 (0.01) |
0.96 (0.01) |
|
2,000 |
0.00 |
0.03 (0.01) |
0.97 (0.01) |
|
2,500 |
0.00 |
0.02 |
0.98 |
where:
• The numbers in parentheses represent the value variation corresponding to an interval confidence of 90% SD.
Specialty: Genetics
ICD-10: ,
