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Amniocentesis pcr or Karyotyping

Amniocentesis pcr or Karyotyping Posted by MONA V.
For single gene defects like beta thalssemia , myotonic dystrophy . Is amniocentesis and pcr done or amniocentesis and Karyotyping . Please clarify . Is PCR only for trisomy21,18,13 and x y chromosome disorders.
Posted by Farrukh G.

The fact that you have asked the question in the way you have raises concern and you need 1-2h reading an undergraduate genetics text.

 

Karyotype - uses metaphase spread and staining to identify and count the number of chromosomes. Can only identify problems with chromosome number (karyotypic abnormalities) or major chromosomal structural defects like translocations.

 

PCR = polymerase chain reaction - technique used to amplify (and then identify) small ammounts of genetic material. Can be quantitative (actually measures ammount of starting material) or qualitative (simply amplifies it). The technique makes use of specific primers (sequences that bind to specific complementary DNA sequences which are heated to seperate the double stranded DNA to single strands). PCR is used for a variety of purposes including identification of mutations (dene defects).

 

For abnormalities of chromosome number, you can use karyotype, FISH, quantitative PCR and a range of other techniques.

You cannot use karyotype or FISH to identify gene defects. You will have to use PCR