DNA sequencing

Dear friends

I made DNA sequencing for my son and the result was that :

DNA sequencing of a B-globin chain:
Double heterozygous:
IVS I-6
Codon 27 ( HB Knossos )

Any idea what does this mean or indicate?

Manal

speaking of DNA.....

Lauryns MD does not want to do a DNA test on her right now, because he wants to keep as much of MY blood in her as possible at this time.? Does that make sense, or does it not matter? I figure they can use some blood when they do her cbc on Nov.6? Any insight would be appreciated! ( he says it would deplete the only fetal hemoglobin she has left?)
   
Christine

Hi Manal,

There is some old information regarding Thalassemia mutations that I came across on the internet sometime back when I was trying to find out about the mutations that my daughter has (she is double/compound heterozygous beta thalassemia major - double heteozygous (or compound heterozygous) means that both the alleles have mutations).

This material is from the book A Syllabus of Thalassemia Mutations (1997) by Titus H.J. Huisman, Marianne F.H. Carver, and Erol Baysal, published by The Sickle Cell Anemia Foundation in Augusta, GA, USA. The material is available under:

http://globin.cse.psu.edu/html/huisman/thals/contents.html

The specific information about the two mutations that you talked about are in the following websites (from the same material):

IVS I-6:
http://globin.cse.psu.edu/html/huisman/thals/beta/IVS-I-6.(T-@C)..the.Portuguese.type.html

Codon 27 ( HB Knossos ):
http://globin.cse.psu.edu/html/huisman/thals/beta/Codon.27.(G-@T)..GCC(Ala)-@TCC(Ser).html

Hope this answers your question. I am not a doctor, so will not be able to explain the information in greater detail

Hi Christine,

The fetal hemoglobin decays in infants are different rates, for some it decays faster than others. In the case on my daughter it went down from mid 10s to high 8s in a week. She lost some more hemoglobin over the next two weeks and needed a transfusion when her hemoglobin level was in the low 7.

I am not sure whether the rate of decay was slightly higher than normal (the doctor had indicated that in thal majors the hemoglobin decays at the rate of 1 per week) because of the blood that was drawn out of her. But now after three transfusions, her pre-transfusion hemoglobin levels are maintained at ~ high 9 and she is most probably settling down to a once a month blood transfusion schedule.

So, if Lauryn is maintaining a hign hemoglobin, and your doctor is comfortable with not doing the DNA sequencing, I think you and Lauryn should be OK, as long as Lauryn gets the required care for thalassemia from him/her.

Remember that the DNA sequencing will only tell you exactly what Lauryn has and what the mutations of the two alleles are - it will not change the type of care that she is currentkly receiving. I think they require around 5cc of blood to do the sequencing, but your doctor may be able to tell you better.

Regards,

Bostonian

Hi Chrisine

The sample neededto make the DNA seq is very small. They took from my son only 2 cm. and i don't think it matters because the sample taken for CBC is much bigger, but at the end the doctor knows better.

Hi Bostonian
Thanks a lot for the links, they seem very helpful.
Hope your daughter is much better now, but did he doctors tell you when she will start chelation and if it is possile for babies to use exjade?

Manal

 

Hi Manal,

Glad to have been able to share information that I had.

My daughter is doing OK now .... thanks for asking. We had asked the doctor regarding chelation and they had indicated that they will monitor her on a regular basis and decide when to start the chelation. Since Exjade has been approved for use with thalassemics 2 years and older, their initial estimate is that they would like to start her when she is around 2 years old so that she can start with Exjade. But this will depend entirely on her ferritin levels, and they have indicated that if she needs chelation earlier, they will put her on the proper medication (I guess it means Desferal) at that time.

How is your son doing nowadays ...... hope he is in good health.

Take care.

Bostonian