THE AMBASSADORS
Health Supplement
THE AMBASSADORS
Health
Supplement
SELECTED STUDIES
Volume 1,
Issue 3
November 1998
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PREVENTION OF GENETIC DISORDERS IN OMAN |
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Genes are the units of heredity. They are sequences of amino acids, which code for particular proteins and ultimately every trait of any life forms. Genes are packed in the every cell's nucleus in structures known as chromosomes. Therefore, genetic diseases are a result of an aberration in the genetic material and can be found in every community on earth.
Every human possesses up to 100,000 genes that not only determine the external human features, like height, hair and eye colour, but also play a role in the metabolic, enzymatic and biochemical processes of the body. In every human, irrespectable of age and state of health, there are some strong and some weak genes. On average, every human has 5-10 genes which are imperfect no matter regardless how young or healthy he or she is. These imperfect genes may show their effect on health in different stages of life.
Nonetheless, new developments in the growing field of genetics have made profound changes in how we understand and practice medicine. New genetic technology is evolving at a dramatic pace. Gene isolation and mapping provide us with a new understanding of how cells grow and function in health and disease. The study of genes and gene products are disclosing secrets of the metabolic process in the cell. The understanding of cell chemistry offers new horizons for therapeutic manipulation and the prevention of illness. The new genetics brought to us not only deeper knowledge of genetic diseases, but also allows a better understanding of common diseases. In conditions such as diabetes, psychoses, hypertension, myocardial infarction, some forms of cancer and arthritis, multiple predisposing genes interact with environmental factors to produce the disease. In the near future, it will be possible to screen families for predisposition to the above-mentioned conditions which will open possibilities for their prevention and pre-symptomatic treatment of these diseases.
The largest world research project is the Human Genome Project. This international collaborative venture is financed by US Energy Department, which aims to map the entire human genome. With recent advances in molecular genetics, analyzing and manipulating individual genes is becoming a increasingly possible. However, gene therapy for common diseases in humans is still a research field. It will not be available for some time as much of the technical and ethical problems are yet to be resolved and overcome in this area.
Genetic Disorders Among Arab Populations
It is estimated that genetic diseases are more common in the Middle Eastern countries than in the West with characteristic disease profile among the Arabs (Teebi & Farag, 1997). This arises because of the following risk factors:
1. The high frequency of advanced parental age. There is an association between advanced age of parents with higher chance of having children with chromosomal rearrangements. Most common condition seen is Down Syndrome.
2. Customary consanguineous marriage is a long-standing tradition, which offers significant social and economic benefits. Because the majority of consanguineous couples have normal children it is not fair to say that consanguinity is a reason for genetic disease. However, consanguineous marriage favours the manifestation of recessively inherited disorders such as metabolic diseases, genetic forms of deafness and blindness, hemoglobinopathies and some types of congenital malformations and mental retardation. Related parents inherit a significant number of identical genes from a common ancestor. In cousin marriages, imperfect genes may become exposed more readily. As one copy of each gene is inherited from mother and one from father, disease may occur if genes inherited from both parents are imperfect. Hence, it is wise to avoid consanguineous marriages in families with a history of genetic diseases (Rajab A, De Louvois J.: 1990, Rajab A, Patton M.: 1997).
3. High frequencies of hemoglobin disorders have been observed in the majority of Middle Eastern countries. In the past, genetic variations of hemoglobin offered protection against death from malaria when treatment was unavailable. WHO surveys indicated that 5-45% of the Middle Eastern population carry genes for hemoglobinopathies.
Genetic Disorders in Oman
We can proudly state that
the information about genetic disease that has been ascertained
in Oman is impressive compared to other countries of the Middle
East. The country's Ministry of Health has considered control of
genetic diseases with special plans to control genetic blood
disorders as a first step. The Genetic Center in Oman is in the
process of being established. Clinical Genetics services have
been operational for the last 5 years at the Royal Hospital, a
national tertiary referral centre. Soon, a cytogenetic laboratory
will be established. The registration of genetic diseases was
started 5 years ago and is characterized by 3 separate
registries:
1) Genetic Blood Disorders (Homozygous sickle cell anemia and thalassaemia major).
2) Dysmorphic syndromes and congenital malformations.
3) Metabolic disorders
The recently formed section of genetic blood disorders will start work towards controlling hemoglobinopathies in Oman and will serve as a model for other genetic diseases (Rajab & Patton, 1997).
A national survey showed that genetic blood disorders are common and that 10% of Omanies are gene carriers for sickle cell anemia and 3% for Beta-thalassaemia. Both conditions will lead to disability and death if left untreated and require life-long medical care. There are around 2000 cases of symptomatic sickle cell anemia, primarily children, which receive treatment in the hospitals of the Sultanate. Each year there are at least 120 cases among the newborn. There are also approximately 300 cases of Beta-thalassaemia in Oman with an annual increase of 20-25 cases.
Modernization of medical services in Oman
The medical authorities
in the Sultanate of Oman are highly dedicated to the prevention
of genetic diseases and minimizing both mental and physical
disabilities due to inborn errors of metabolism,
neurodegenerative diseases, chromosomal rearrangements,
congenital malformation syndromes, genetic blindness, and
deafness. The care of the handicapped is of increasing concern to
public health and social affairs.
The favourable socio-economic development in Oman under the leadership of His Majesty Sultan Qabus bin Said have been translated into superior health care services. As infectious diseases and malnutrition disappeared, genetic diseases now account for an increasing proportion of death, handicap and disability.
The medical services have reached such standard in Oman that many patients who would formerly have died are now surviving into adult life. The number of children with chronic disorders are rising progressively, as too is the cost of their treatment. Up to 5-10 fold increase in the number of people with genetic diseases is expected over the next 50 years if there is no prevention. This will drain the health resources and affect adversely family and social life. Additional funds will be required from social services for life-long financial support of the handicapped plus the provision of special educational and rehabilitation needs for thousands of disabled.
With the help of genetic counseling and health education, it is possible to bring an understanding of genetic diseases to the community. Offering premarital screening and population screening opens the possibility for the avoidance of genetic disease. It would be unlikely that marriage will be arranged between two individuals who are both known to be carriers of the genetic disease, especially in a family which has already experienced the hardship of the genetic disease.
The successful birth spacing programme in the Oman will result in smaller size families. Despite the growing demand for providing genetic services to families to ensure their children will not suffer from genetic disorders, it is difficult to achieve complete control over genetic diseases without access to the ante natal diagnosis.
An upgrading of current genetic services into a proper Genetic Centre in Oman will not only provide diagnostic and counseling facilities, but will carry on with prevention programmes, population education, train health professionals and perform research studies. The treatment and prevention of genetic diseases is impossible without adequate diagnostic laboratory facilities in molecular genetics, cytogenetics and metabolic medicine.
Control of genetic diseases is a challenging task requiring hard work and dedication from geneticists, medical, paramedical staff and the community. Community genetic services are relatively inexpensive and set against the great social and financial burden of chronic disease are very cost-effective. According to WHO Technical Report (1996), one of the main problems in delivering genetic services appears to be the difficulty of informing both, the health professionals and the community of the real significance of the genetic problem.
Yet, it is not always possible to treat the genetic disease. Some conditions can be managed with life-long medications, special diets, regular blood transfusions or organ transplantation. For many of the genetic diseases there is no radical cure. However, it is possible to avoid or to control genetic diseases in the populations. A model example comes from Cyprus where B-thalassaemia, once a common disease, has now been completely eradicated.
Dr. Anna Rajab,
MBBCH (Kiev), DCH (Dublin), MRCP, PhD (London), is the founder of
genetic services in the Sultanate of Oman. She completed her
post-graduate studies in clinical genetics in St. George's
Hospital Medical School, London in 1997 after 26 years of
experience in obstetrics, internal medicine, neonatology, general
pediatrics, and clinical genetics. Her areas of interest are
clinical & population genetics, genetic epidemiology and
prevention of genetic disorders. Dr. Anna has many excellent
publications in international scientific journals.
References:
Rajab A, De Louvois J. (1990) Survey of infections in babies at the Khoula Hospital, Oman. Annals of Tropical Pediatrics; 10:39-43.
Rajab A. (1996) Bonneau syndrome: a further case report. Letter to the editor. Clinical Dysmorphology (5): 1-4.
Rajab A, Freeman NV, Patton M. (1996) The frequency of posterior urethral valves in Oman. British Journal of Urology (77):900-904.
Rajab A, Freeman NV, Patton M. (1997) Hirschprung's disease in Oman. J Pediatr Surgery ;32(5):724-727.
Rajab A, Patton M. (1997) Major factors determining frequencies of Haemoglobinopathies in Oman. Letter to the Editor. American Journal of Medical Genetics; 71:240-242.
Rajab A, Vaishnav A, Freeman NV, Patton M. (1998) Neural tube defects and Congenital Hydrocephalus in Oman. Journal of Tropical Pediatrics (In print)
Rajab A, Patton M. A study of Consanguinity in the Sultanate of Oman. Difficulties in accurate measurements of Inbreeding. Annals of Hum Biol (in print)
Rajab A, Patton M, Modell M . The development and use of a National Haemoglobinopathy Register in Oman. (in preparation)
Rajab A, Thomas C. Facial clefts in Oman. (in preparation)
Rajab A, Patton M, Modell B. The development of a Genetic Register using Tribal information in Oman. (in preparation)
Soliman AT, El-Nawawi AA, El-Azzoni O, Amer SA, Rajab A. (1995) Seip-Berardinelli lipodystrophy: Report of three cases and their endocrine functions. Annals of Saudi Medicine; 15(5):501-505.
Soliman AT, Bappal B, Darwish A, Rajab A, Asfour M. (1995) Growth hormone deficiency and empty cella in DIDMOAD syndrome : an endocrine study. Arch Dis Child; 73:251-253.
Soliman AT, Rajab A. (1996) Empty cella in Bardet-Biedl . Metabolism, (45): 1230-1234.
Soliman AT, Rajab A. (1996) Pyknodysostosis. Arch Dis Child (75):242-244.
Soliman A, Rajab A, Aslami I, Aziz Bedair SM. (1998) Recessive Robinov syndrome: With Emphasis on Endocrine Functions. Metabolism; 47(11):1-8.
Suliman AT, Rajab A, El Zalabany M, Al Salmi I, Abdel Fattah M. (1998) Defective Growth Hormone (GH) Secretion in Short-Term Treatment in Noonan Syndrome. Indian J. Pediatr; 65: 661-669.
A.S. Teebi & T.I. Farag
(1997). Genetic Disorders Among Arab Populations. Oxford
Univ. Press, NY.
