IUBio GIL .. BIOSCI/Bionet News .. Biosequences .. Software .. FTP

[Re] Chromosome 6

Jeff Taylor jtaylor at cadvision.com
Mon Oct 2 10:08:30 EST 1995

nsuyeda at aol.com on 29-Sept-95 writes:

>A friend's amniocentesis shows an abnormal wide band on six. The lab's
>first response is to .......

This is regarding your question about your friend's amniocentesis.  There is a

question I would have for you (or her).  If they are normal, healthy parents 
with a normal sonogram why have they had an amnio?  I am going to assume the 
answer to this is because of the mother's age.

You say there is a band that is wider than normal.  (It would help immensely 
to know which band).  This basically means there is extra DNA present.  There 
are 2 possibilities:

1) The extra DNA does not contain any genes (nor affect any genes normally 
present in this region).  There would most likely be no repercussions to the 
baby.  The only way of knowing this for sure is if one of the parents has the 
same anomaly.  That is why the first thing the lab is doing is to test the 

2) The extra DNA contains genes.  If this is the case then the baby has one 
too many copies of the extra gene(s).  Because a chromosome analysis is 
looking for gross chromosomal abnormalities, the fact that they have found 
something means that there is a lot of extra DNA.  This is not good news.

To do any kind of research you would have to know the specific band on 
chromosome 6 that is affected and then go to a medical library (most 
universities have one).  You would then have to check the literature to see if

there are any reported cases of people having extra DNA (trisomy) in this 

To date 23 patients with partial trisomy of the long arm of chromosome 6 have 
been reported.  These all involve duplication of more than a single band so 
are more severe than what you say is a single abnormal wide band. Therefore it

is impossible to speculate on your case.

The best news would be for one of the parents to have the same phenomenon.  
Otherwise, I feel there may very well be physical and/or neurological 

Hilary Taylor
(MSc Human & Medical Genetics)

More information about the Biochrom mailing list

Send comments to us at archive@iubioarchive.bio.net