whournameiz
Forum Senior
Topics: 40
Posts: 94
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anyone understand these?
Father mother not affected,all 3 offsprings affected: reason•
germline mosaicism,
variable expression,
pleiotropy.
Cystic fibrosis:All previous genrn +/+ ,father +/+ ,mother+/delta I 507--• child F delta 508/delta I 507 • reason:
unipaternal disomy,
unipaternal monosomy,
dipaternalism,
unmasking of splice gene.
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| doc179
Forum Guru
Topics: 67
Posts: 1,217
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may be germline mosaicism for the first one, can not understand the second, does that mean that the child does not have CF, I think so cos the deletions for the CF gene is at different places in the child. If thats the case. But none of the options seem right, what is dipaternalism?
looks like father has a deletion in 508 and mother has it in 507.
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| whournameiz
Forum Senior
Topics: 40
Posts: 94
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yea i looked up dipaternalism...does not exist!
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| doc179
Forum Guru
Topics: 67
Posts: 1,217
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yeah me too, did a google search, it does not exist. where is the qn from? do they really give such an option? weird sin't it?
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| new_n_lost
Politically InCorrect
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To Whournameiz.............. PLZ PLZ when u post Exm Question plz DO mention them in the Post.
The Answer to first one is Germline Mosaicism = Transfer of the Gene to the Child even when the Parents r not effected.
To the 2nd Question.
Paternalism is the Term used in economics where the subject is well provided while not having any rights or such recognition.
the answer in my view shud be the Unmasking of a Splice Gene.
Reasoning :- i dont know wht the person who actually had the question understood when he/she had the question but by stating +/+ means the person is Affected or has the disease in the genes but if the generation or the parents have the Active Disease is not understood. Then they mention the Child having the Delta F508 deletion. Now we all know that CF is an autosomal Recessive Disease and the Mutation which largely is found in most of the cases of CFTR gene called DELTA F508. If the Question says that the child has had that particular mutation in the Allele of CFTR gene then the child is having CF hands down. The question arises why didnt the parents have it although they were consider positive i dont know.
I m searching for other options and seeing which fits best so plz do join the discussion over this question.
I m also amazed that any person cud really remember this question when it completely looks like a Experimental one.
Edited by new_n_lost on 06/07/07 - 11:13 AM
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| new_n_lost
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The CFTR gene encompasses approximately 180,000 base pairs on the long arm of chromosome 7. The protein contains 1480 amino acids. More than 1000 disease-associated mutations have been described in the coding sequence, messenger RNA splice signals, and other regions. These mutations can be classified on the basis of the mechanism by which they are believed to cause disease. The most common mutation, which is termed  F508 and is present in approximately 70 percent of defective CFTR alleles and in 90 percent of patients with cystic fibrosis in the United States, is categorized as a class II defect. CFTR with the F508 mutation lacks a phenylalanine (F) residue at position 508. The defective protein retains substantial chloride-channel function in cell-free lipid membranes. When synthesized by the normal cellular machinery, however, the protein is rapidly recognized as misfolded and is degraded shortly after synthesis, before it can reach its crucial site of action at the cell surface. Like F508, several other clinically important mutations ��" such as N1303K, G85E, and G91R ��" lead to misfolded CFTR protein that is prematurely degraded.
Figure 5. Categories of CFTR Mutations.
Classes of defects in the CFTR gene include the absence of synthesis (class I); defective protein maturation and premature degradation (class II); disordered regulation, such as diminished ATP binding and hydrolysis (class III); defective chloride conductance or channel gating (class IV); a reduced number of CFTR transcripts due to a promoter or splicing abnormality (class V); and accelerated turnover from the cell surface (class VI).
http://content.nejm.org/cgi/content/full/352/19/1... for further reference.
Attached Files:
CF Defects Class.jpg (41 KB, 16 downloads)
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FORUM RULES-- Those who believe in telekinesis, raise my hand. I get enough exercise just by pushing my luck --P4U World.." The pure and simple truth is rarely pure and never simple."
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| mytime
Kick my butt!
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yeah that's what i thot.
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| new_n_lost
Politically InCorrect
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regarding my Statement in the 2nd Question that the Child has CF Hands down, i kinda seem to have missed the point that Its Autosomal Recessive The Child needs to have the Same Deletion on both the Alleles he has received from the Both Parents i.e Delta F508 from both Mother and Father in order to have the Active Disease. But he has a Allele which has Delta F508 mutation and other having Delta I507 deletion thus he can not have the Active disease although he may be a Heterzygous for the Disease.
But the Appearence of the Delta F508 is due to the Unmasking of the Splice gene.
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FORUM RULES-- Those who believe in telekinesis, raise my hand. I get enough exercise just by pushing my luck --P4U World.." The pure and simple truth is rarely pure and never simple."
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| doc179
Forum Guru
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very nice explanation 
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| whournameiz
Forum Senior
Topics: 40
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i should put exam question? I thought that wasn't allowed...
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| silver
Forum Guru
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the point is that it's better if you mention that these are exam questions. that way, ppl will be informed and attempt the ques. accordingly. otherwise, ppl will think it's a concept that you're trying to clear up on your own, or a personal ques. you're wondering about, and might not give it as much attention.
also knowing a ques. is from an exam, helps to do a quick self-assessment for ppl on the forum when they come across such questions.
and just make sure you write the entire ques. ......i know of some ppl who have been spending quite a bit of time on this ques. of yours, and eventually have gotten frustrated cuz your wording was incomplete.
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