Gene Therapy: The Ethical Dilemma

When most people think of DNA, they envision it as the inherited substance that has made them what they are. They also see it as something that’s sacrosanct, written in stone, enduring from cradle to grave.

As it turns out, they could be wrong. Modern science can alter the DNA sequence, and it can do this for one cell, for multiple cells, or for an entire organism. Why would one wish to make the effort, though, and what are the implications?

What Gene Therapy Involves

In human beings, two types of genetic modifications are under investigation: germline and somatic. Each involves the introduction of a gene or gene segment into cells in need of adjustment, and neither is yet out of the experimental stage.

Germline Gene Therapy

Human germline genetic modification, or HGGM, aims to correct a malfunctioning or nonfunctioning genetic component by altering the DNA of human eggs or sperm. This theoretical, untried intervention would permanently affect the genetic makeup of future generations while having no effect whatsoever on the donors.

Somatic Gene Therapy

Somatic genetic modification attempts to treat or cure medical conditions by directly targeting the DNA sequence of diseased organs or tissues at the cellular level. Since somatic genetic modification makes no changes to the patient’s eggs or sperm, these updates will affect only the recipient and not pass on to future generations.

How Gene Therapy Is Performed

The practice of gene therapy involves transmitting genetic material into the cells in question. Since direct insertion has proven ineffective, researchers must employ a vector for this purpose. Some of the most effective carriers have proven to be modified viruses that work by infecting the cell to make it more receptive by weakening its resistance.

The means of delivery can also vary. Some methods introduce the vector directly to the patient’s body either intravenously or through inoculation. Others involve removing a patient’s cells and exposing them to the vector in a test tube environment before returning them to the body.

The Future of Gene Therapy

Although still in its infancy, successful somatic gene therapy could conceivably treat or even cure such diseases as:

– Cancer.

– Chronic granulomatous disease.

– Cystic fibrosis.

– Huntington’s disease.

– Parkinson’s disease.

– Severe combined immune deficiency.

– Sickle-cell anemia.

– Thalassemia.

If successful, the introduced gene will generate a working protein that alters the structure of the DNA to correct the genetic malfunction that’s causing the problem.

Ethical Considerations

While somatic gene therapy may someday routinely cure disease and rectify inherited defects, the ability of germline gene therapy to alter the DNA of future generations raises some ethical questions. The prospect of custom ordering a red-haired, brown-eyed child with an IQ of 165 might entice some future parents, but potential legal and moral objections could halt such creativity before it ever gets off the ground.

The Terrible Effect of Tissue Nematodes to Human Health

Filariasis, onchocerciasis, loiasis, dracunculiasis are tropical diseases. Wuchereria affects about 200-300 million people. Onchocerca affects millions of people in Africa and Central America. What is the medical concern about these strange ailments?

Wuchereria bancrofti

This causes filariasis. It occurs in the tropics and its mode of transmission through biting by the females mosquito (especially Anopheles and Culex species) on the skin of Humans, depositing the infective larvae. The larva penetrates the skin, enter a lymph node, and after a year, mature to adults that produce mecrofilariae. These circulate in the blood, chiefly at night, and are ingested by biting mosquitoes. Within the mosquitoe, the micro filariae produce infective larvae that are transferred with the next bite. Humans are the only definitive hosts.

Adult worms in the lymph nodes cause obstruction of lymphatic vessels, causing edema of the legs and genitalia (elephantiasis). Laboratory diagnosis is based on blood smears taken from the patient at night to reveal the microfilariae. A yearly dose of drug therapy would kill the microscopic worms circulating in the blood. Drugs such as Diethylcarbamazine (DEC) and ivermectin are most trusted drugs for the effective treatment therapy of filariasis. Even if these drugs do not totally kill all the adult worms, they prevent the affected person from spreading it to someone else. But even after the death of all Adult worms, there could still be swellings of the genitals, breast, arms, legs etc. Management therapy can then be applied by

1. Daily cleaning up of swollen regions with careful administration of soap and water.

2. Application of anti-bacterial cream/ointment on any wounds.

3. Elevation and constant exercise of swollen limb to spread the fluid and improve lymph flow.

Prevention involves mosquito control with insecticides and the use of protective clothing, mosquito netting and repellents.

Onchocerca volvulus

This causes onchocerciasis. Vectors of Onchocerca volvulus (black flies) develop in rivers and people who live along those rivers are affected. Infection rates are often over 80% in endemic areas. Humans are infected when the female black fly simulium deposits infective larvae on the skin while biting. The larvae enter the wound and migrate into the subcutaneous tissue, where they differentiate into adults, usually within dermal nodules. The female produces microfilariae that are ingested when another black fly bites. The microfilariae develop into infective larvae in the fly to complete the cycle. Humans are the only definitive hosts.

Infalmmation occurs in subcutaneous tissue, and pruritic papules and nodules form. Microfilariae migrate through subcutaneous tissue, ultimately concentrating in the eyes. They cause lesions that can lead to blindness (“river blindness”). Laboratory diagnosis is based on Biopsy of the affected skin which would reveal microfilariae. Treatment is based on drug therapy. Drugs which can be used are as follows

1. Diethylcarbamazine (DEC)

2. Suramin (Antrypol)

3. Amocarzine (CGP-6140)

4. Ivermectin

5. Surgical (Nodulectomy) in severe cases.

Prevention involves control of the black fly with insecticides.