Hello,
I am studying MAO-A polymorphisms that consist on a series of repetions of promoter region. Therefore, I expect to obtain up to 5 different PCR bands (291,321,336,351,381bp) depending on the polymorphism presented in the patient.
Logically, I must to get one or two bands as maximum. However, sometimes, I find three bands that correspond to the specific size of the fragments 336,351,381 that own to allele 3.5; 4 and 5.
Could somebody help me please?
Thanks in advance
it is possible that one of the bands is a non specific amplification of someting else....does one size always happen whatever the sample?. Alternatively is there another organism contaminating your dna ( is this a soil bacterium DNA) contributing teh third band?
No, it does not happen for all the cases. I can get normal number of bands (homozygous or heterozygous) in the same PCR. The samples come from peripheral blood of kids. I already tried using different extractions for the same case and is still get the same results. Maybe I must try changing the reagents or modifying the PCR protocol? Although is weird this bands are obtained only in some samples.
then how about 2 alleles inherited from one parent and one from the other. Parental samples would be needed to test this . It would need a partial trisomy or translocation of part of the chromosome with your sequence in one parent. Both of these situations are rare so if you are getting many such samples the answere probably lies elsewhere
MAO-A is on the X-chromosome, right? So perhaps you have an XXY individual, or an individual that is carrying, as mentioned above, a translocation. Your samples are from "kids"...how many? Are they related? Do you know the parents genotypes? Is there a possibility of contamination? Just a few thoughts. Obviously don't answer with any information that would compromise confidentiality. Good luck!
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