Which one of the following can help in the diagnosis of a genetical disorder?

Options

A. ELISA
B. ABO blood groups
C. PCR
D. NMR

Answer

To determine which option can help in the diagnosis of a genetic disorder, we need to analyze each of the provided options:

1. **ELISA (Enzyme-Linked Immunosorbent Assay)**: This technique is primarily used to detect the presence of antibodies or antigens in a sample, typically blood. It is not specifically designed for diagnosing genetic disorders, as it does not analyze genetic material.

2. **ABO Blood Group**: The ABO blood group system categorizes blood into four groups (A, B, AB, O) based on the presence of specific antigens on the surface of red blood cells. While important for blood transfusions and compatibility, it does not provide information about genetic disorders.

3. **PCR (Polymerase Chain Reaction)**: PCR is a powerful technique used to amplify small amounts of DNA, making it possible to analyze genetic material in detail. This method is widely used in genetic testing to identify mutations or abnormalities in genes associated with genetic disorders. Thus, it serves as an effective diagnostic tool for genetic defects.

4. **NMR (Nuclear Magnetic Resonance)**: NMR is primarily used for imaging and analyzing the structure of molecules, including proteins and metabolites. It is not a standard method for diagnosing genetic disorders.

Based on this analysis, the most suitable option for diagnosing a genetic disorder is **PCR (Polymerase Chain Reaction)**.

### Final Answer:
**PCR (Polymerase Chain Reaction)**