nlr1977
Senior Member
Registered: 08/28/07
Posts: 16
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| | 07/20/10 at 05:09 PM | Reply with quote | #1 |
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There is no such thing a s a carrier... you either have it or you don't.
Every body has CTG repeats on their DNA. Non affected people have CTG repeats between 5 -35. They are stable repeats. Each person has 2 sets of CTG repeats in their DNA.
Anything 36 or above is unstable.
For example you have a male with repeats 12 and 28, and a female with repeats 8 and 17. When they conceive a child each will pass on a set of repeats.
For example the Dad passes on his 12 repeat and the mother passes on her 17 repeat, the child will have repeats of 12 and 17.
For the FATHER TO PASS IT ON
A Male with MMD ~ they will have one stable repeat such as 18 and an unstable repeat such as 56. If they have a child with a female with normal repeats, eg. 12 and 25, the mother may pass on her 25 repeat with the Father's 12 repeat, their child will be unaffected.
But if the father passes on the unstable repeat of 56, it may multiply, (as did in my case... to 133) this child will be born with a repeat of eg. 133 from the father and a repeat of 25 from the mother.
Now if this child is a boy, the case will be the same. Their repeats will be 25 and 133. When they have a child, they may pass on the normal repeat or the unstable repeat, just as their father did.
However, it is not know for the fathers repeat to multiply greatly, eg, the 133 repeat, may decrease.
If the child born is a female, this is where Congenital Myotonic Dystrophy can occur.
FOR the MOTHER TO PASS IT ON
In my case I passed on my unstable repeat of 133 and my husband passed on his repeat of 12 to our son. My son was born with repeats of 12 and 1033. My repeat multiplied by 10 and my son was born with Congenital Myotonic Dystrophy, meaning it was seen at birth.
He had trouble breathing, swallowing, sucking and was very floppy.
I had no signs of this and would probably never have know I had it if it hadn't been for my son.
My first child doesn't have it.
Affected Parents
Some people only ever have a stiffness in their hands or cataracts.
There is no 2 people the same. Some have high repeats and some have low repeats.
Generally, the Adult onset will occur sometime during adulthood. But this isn't a rule.
My son has repeats of 1033, he is 4 and is still not walking , talking, feeding himself, but is making great progress with all these areas. Friends I have met (worldwide through this website) have children with 1500 repeats, who were slightly delayed in all areas, but are walking, talking, eating and toilet trained at 2 years old.
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pookie
Senior Member
Registered: 03/10/09
Posts: 16
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| | 07/21/10 at 04:09 AM | Reply with quote | #2 |
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I would just like to add a small note to this very informative and useful post.
When i discussed repeat numbers of my wife with the neurologists at the national hospital for neurology in the uk ,they advised that in the uk consultants avoid advising already diagnosed patients of the repeat numbers completely.They told me this is because in terms of symptoms and their severity it is no use as an indicator at all.As shown by nlr1977s examples you can have a very high repeat number and be almost symptom free with nothing showing until late in life or you can have a low number and be severely affected from an early age.
Pookie
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nlr1977
Senior Member
Registered: 08/28/07
Posts: 16
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| | 07/25/10 at 03:49 PM | Reply with quote | #3 |
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Another piece of information I was given by my Geneticist is,
* Repeat numbers may vary, depending on where the blood sample is taken. For example, blood is usually taken from the arm, where if you have great upper body strength but low muscletone/strength in your legs your reading may not read the same as if it was taken from your legs. However, it is just not the done thing to take blood from other parts of the body.
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