Medical Enigma   



Medical Enigma

 
Doctors finds the men of science hard at work sifting through fact and fiction to find conclusive answer as to what triggers a disease - is it our genes, partially determined by our ethnicity, or is it the environment or are all of the aforementioned to blame in varying degree ?

Why are certain ethnic groups more prone to heart disease and others more susceptible to developing diabetes? Amidst much head scratching and heated debate, most researches have come to a broad conclusion that environmental factors encompassing multifarious factors such as diet, lifestyle, income, education, socia-economic status and access to health care are the likely causes.

Of late, genetic factors are also being studied but the true reason for the onset of any disease is yet to be conclusively determined. According to Francis S Collins, "A true understanding of disease risk requires a thorough examination of root causes. Race and ethnicity are poorly defined terms that serve as flawed surrogates for multiple environmental and genetic factors in disease causation." Collins is the director of the National Institute of Health in the United States and was previously the director of the National Human Genome Research Institute.

Here we take a glimpse at the rising numbers of three common diseases that appear to afflict a particular ethnic group more relative to others.

HEART DISEASE
In the United States, African Americans have high rates of heart disease including coronary artery disease (CAD), stroke, high blood pressure and heart failure, while more than one quarter of Mexican Americans have some form of heart disease. People of South Asian descent are also in the high-risk group, but those of Japanese descent have a lower risk. It has also been noted that Native Americans had very low rates previously but at present, heart disease has become the leading cause of death in his ethnic group. There were also studies that found differences in the way various ethnic groups responded o different drugs.

According to the American Heart Association (AHA), 40 per cent of both African American men and women have some form of heart disease.
In comparison, the numbers for Caucasians are about 30 per cent for men and 24 per cent for women.

Although there are clues here pointing to the role ethnicity may play in heart disease, do bear In mind that this is just a general picture that needs more extensive research in order to confirm a conclusive trend.

The National Institute of Health in the States is currently funding a large project in search of genes that may cause heart disease. The study, initiated in 2000 is tracking heart disease in four major ethnic groups - Caucasians, people of Hispanic descent, African Americans and Chinese Americans. There have also been other studies that have found some genetic differences among the races. One discovered that 13 per cent of African Americans carry a gene change that puts them at greater risk of having a rare kind of abnormal heart rhythm. This gene occurs at a much lower rate in Caucasians and Asians.

But as researchers discover genes that can lead to heart conditions, they may also find that individuals who have these genes do not necessarily get the disease, as there is a complex relationship between genes and the environment.

DIABETES
Diabetes mellitus has become a major global health issue. In fact, the potential numbers projected by WHO is truly frightening. An estimated 30 million people worldwide had diabetes in 1985. A decade later, it was estimated to have catapulted to 135 million. In 2000, the numbers shot up to 171 million and by 2030, it is projected to further double to at least 366 million.

Diabetes is a chronic disease that has no cure and although scientists cannot explain why it happens, it appears that both genetic factors and environment play a role. Although the prevalence of diabetes varies according to ethnicity, it is highest in developing countries, newly industrialised nations and amongst the disadvantaged groups in developed countries.

Due to population growth, ageing, unhealthy diets, obesity and sedentary lifestyles, there is a growing incidence of type 2 diabetes that accounts for about 90 per cent of all diabetes cases. The risk of type 2 diabetes increases with age, and most develop the disease after age 30. Also, type 2 diabetes runs in families but it was noted that usually, it takes another high risk factor such as obesity to bring on the disease. In developing nations, those most frequently affected are between
35 and 64 years of age. In developed countries, it affects those above the age of retirement.

Interestingly, exceptionally high occurrences of diabetes has been noted in populations that have newly transitioned from traditional to modern lifestyles. For example, diabetes in adults ranges from less than two per cent in Tanzania and Mainland China to 40 to 50 per cent in urban Papua New Guinea. This reflects changes in environment and lifestyle factors such as diet and physical inactivity.

In a paper titled Global Prevalence of Diabetes by Wild et al, 2004, India was ranked at the top with the highest number of estimate cases affecting 31.7 million people in 2000. This number is expected to reach 79.4 million people by 2030. China hogs the second spot with an estimated 20.8 million affected people in 2000, projected to reach 42.3 million by 2030. This was followed by the United States, Indonesia, Japan, Pakistan, Russia, Brazil, Italy and Bangladesh. However, by 2030, the rising number of diabetic patients in the Philippines and Egypt will propel these countries within the top 10 bracket.

In Malaysia, WHO has estimated that the number of diabetic cases will rise from 942,000 in 2000 to 2.48 million in 2030. The Second National Health and Morbidity Survey by the Institute for Health in Malaysia on diabetes affecting adults aged 30 years and above, revealed geographical variations in the observed prevalence of diabetes by states. The highest numbers occurred in more developed states like Selangor and Penang.

By ethnicity, the prevalence of recorded diabetes cases in Indians was significantly higher compared to other races. In comparison, the Other Bumiputeras recorded the lowest prevalence, indicating that populations whose lifestyles still adhered closely to their traditional ways seemed to fare better. There are also cases of migrant populations, for example Asian Indians who have migrated to various part of the world, recording a high prevalence of diabetes.

CANCER
In Malaysia, according to Yusof Mohamed Aris, Research Manager of MAKNA (National Cancer Council), researchers cannot pinpoint the actual cause of cancer and why one ethnic group could eat a higher risk than another as no known, specific research using ethnicity as a base has been conducted thus far. However, he did state hat MAKNA is currently working with various local universities to conduct a study on cancer in relation to diet.

As Yusof pointed out, one could greatly reduce chances of developing cancer by limiting risk factors such as smoking, a high-fat diet, alcohol abuse, overweight, a low-fibre diet, air pollution and stress. The same holds true for most types of chronic diseases.

According to MAKNA, nearly 70,000 new cancer cases were diagnosed among Malaysians in Peninsular Malaysia between 2003 and 2005. This was based on The Cancer Incidence in Peninsular Malaysia 2003 - 2005 report published by the National Cancer Registry (NCR).

From the report, a surprising finding was the high incidence of leukaemia among Malay males, that otherwise rates as the third most frequent cancer among all males but the second highest amongst Malay males.

Yet another unexpected finding was that prostate cancer was the second most common cancer in Indian males. The cancer ranked fourth among male cancers in Malaysia. However, the report noted that this finding for Malaysian Indian males "could be due to a chance variation in a smaller sample compared to the other major ethnic groups."

Large bowel cancer appeared to be the leading cause of cancer in Chinese males. In Indian males, the most frequent cancers were large bowel, prostate, stomach: lung and lymphoma. Breast cancer remains the most common cancer among women across all three ethnic groups.

In an alternative report published by the NCR on cancer statistics in Peninsular Malaysia in 2006, a total of 21,773 cancer cases were diagnosed among Malaysians affecting 9,974 males and 11,799 females. According to the report. Cancer seems to be more prevalent amongst Chinese versus Malays and Indians.

Colorectal cancer was the most frequent type of cancer affecting males in all three major ethnic groups. Its incidence was highest amongst Chinese at 18.8 per cent, in comparison with Malays at only 15.4 per cent and Indians: 11.6 per cent. For females, breast cancer still ranked the deadliest among all cancers, affecting 32.4 per cent of Malay women, 31.1 per cent of Chinese women and 30 per cent of Indian women.

To summarise, what we have now are merely numbers and statistics but ultimately no major conclusive evidence that our ethnicity has a decisive bearing on the diseases that we suffer, as most reports have pointed largely to environmental causes as the main culprit. It really is up to the individual, regardless of race or ethnicity, to take their health into their own hands and minimise the known causes that trigger fatal diseases in our diet, environment and lifestyle.
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Happy reading,
Evelyn


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