Molecular Genetics

Genetic science has emerged from the study of chromosomes to its specific function identified by characterization of genes located on each chromosome. The characterization of every gene is still in progress. Certain genes are identified for their specific function and having their important application in prevention of disease. These include identification of gene for

• Beta Thalassemia
• Duchene Muscular Dystrophy
• Spinal Muscular Atrophy
• Cystic Fibrosis
• Rett Syndrome
• Fragile X syndrome etc.

With the availability of advances in molecular techniques like

• PCR
• Northern blot
• Southern blot
• DNA sequencing
• Microarray

it has become possible to diagnose every genetic disorder that has been known.

How the molecular diagnosis is made:

Molecular diagnosis requires study from DNA sample. This can be carried out either from blood, chorionic villus or amniotic fluid. Separated DNA than amplified by PCR technique using specific primer.

For prenatal diagnosis of single gene disorders the most important part is the identification of carrier status of parents & its screening. Once this is done, prenatal diagnosis can be possible. For example in prenatal diagnosis of ß -Thalassemia, first thing is to identify the type of mutation in the parents, followed by mutation search in CVS or Amniotic fluid DNA, by PCR or B- Globin gene sequence study.

Similarly for any single gene disorder index case diagnose by mutation analysis is must before proceeding for prenatal diagnosis.