Question

QUESTION 7.

Assay question

Duchenne muscular dystrophy is one of the sex-inherited disease. Write a report about the mutation that caused the disease, symptoms, genetics therapies, include a minimum

of one human pedigree that show the disease.

Note:

1. A minimum of THREE scientific papers are encouraged to be used

2. Include a reference list with proper citation (Harvard style).

3. The report should not exceed 100 words

Answer 1

1) Ans,) Duchene muscular dystrophy (DMD) is an inheritable condition that is one of nine types of muscular dystrophy. It is characterized by progressive muscle wasting (atrophy) and weakness in the skeletal and heart muscles, leading to a decline in muscle function and heart problems.

Causes:

The disease is caused by a mutation in the DMD gene, which encodes for a protein called dystrophin. Dystrophin acts to protect the muscles at each contraction, and a lack of dystrophin results in an accumulation of damage and eventual death of the muscle cells.

Symptoms may include:

The following list includes the most common signs and symptoms in people with Duchenne muscular dystrophy (DMD). These features may be different from person to person. Some people may have more symptoms than others and symptoms can range from mild to severe. This list does not include every symptom or feature that has been described in this condition.

Delayed motor development (taking longer to learn to sit, stand, or walk)

Enlarged calf muscles (pseudohypertrophy)

Muscle weakness that gets worse over time

Toe walking or waddling gait

Using hands to get up off the floor (Gower's maneuver)

Progressive enlargement of the heart (cardiomyopathy)

Gene therapy

Our cells have evolved mechanisms to prevent intrusion of foreign molecules. To overcome this we use vectors, or carriers, to carry the new gene into the cell. Currently, the most promising approach is based on the use of a harmless virus called Adeno-associated virus (AAV) as a vector. Viruses have evolved to recognise certain cells and then insert themselves via the cell membrane, and deliver their genetic material into the cell (usually making us feel unwell). However, if scientists remove the unwanted, disease-causing genes and replace them with appropriate beneficial genes, they could restore gene expression. This is the basis of the ‘gene therapy’ that is causing great excitement at the moment.

One challenge of DMD gene therapy is that the dystrophin gene is the longest known gene. Because of this size, it is impossible to insert the entire dystrophin DNA into the AAV vector. So, researchers have created microdystrophin - a shortened version of the dystrophin gene which can fit into the AAV vector. Gene therapy using microdystrophin has successfully been tested in animal models of Duchenne muscular dystrophy. A shortened, but functional, dystrophin protein is produced using this method.

Other types of gene therapy

We can’t leave gene therapy without mentioning CRISPR /Cas9. This has been in the news recently and is a technique that could be used to treat a wide range of genetic diseases, including DMD. CRISPR/Cas9 is an exciting genetic engineering technique with two key components: 1) Cas9 which is an enzyme that can cut DNA at a precise point and 2) CRISPR, a short strand of RNA (a chemical messenger similar to DNA).