Creation Studies Institute
Sickle Cells
 


Sickle Cell Anemia: The Poster Child for Beneficial Mutation

At the Creation Studies Institute we often get emails from those who are debating their evolutionary friends and acquaintances concerning the Theory of Evolution (ToE) and Creationism. Inevitably, sooner or later, the subject of beneficial mutations will be broached. Beneficial mutation is one of the two factors supposedly driving the evolutionary engine that, given enough time, causes molecules to become men. The other factor is natural selection, and these two mechanisms are allegedly capable of producing the upward, increasingly complex, changes hypothesized by the ToE.  These major changes that supposedly take place over hundreds of millions of years have been described by the term “macroevolution.” This is contrasted to the minor variations within a particular group of living organisms. These minor variations or adaptations are given a correspondingly less significant designation, e.g. microevolution.

What is Sickle Cell Disease?

Sickle cell disease is one of a group of disorders that affects hemoglobin. This is the molecule in red blood cells that delivers oxygen to cells throughout the body. People with this particular hemoglobinopathy (autosomal recessive) have atypical hemoglobin molecules called hemoglobin S, which can distort red blood cells into a sickle, or crescent, shape that hematologist’s label drepanocytes.

Sickle cells
Sickle cells (Drepanocytes)

The signs and symptoms of sickle cell disease are caused by the sickling of red blood cells. When red blood cells sickle, they break down prematurely, which can lead to anemia. Anemia can cause shortness of breath, fatigue, and delayed growth and development in children. The rapid breakdown of red blood cells may also cause yellowing of the eyes and skin, which are signs of jaundice. Painful episodes can occur when sickled red blood cells, which are stiff and inflexible, get stuck in small blood vessels called capillaries. These episodes deprive tissues and organs of oxygen-rich blood and can lead to organ damage, especially in the lungs, kidneys, spleen, and brain. A particularly serious complication of sickle cell disease is high blood pressure in the blood vessels that supply the lungs (pulmonary hypertension). Pulmonary hypertension occurs in about one-third of adults with sickle cell disease (SCD) and can lead to heart failure (U.S. Library of Medicine 2007).

People with SCD are born with two Sickle Cell genes, one from each parent, e.g.  homozygous or hemoglobin (Hgb) SS. If you only have one Sickle Cell gene, it's called Sickle Cell trait, e.g. heterozygous or Hgb. AS. About 1 in 12 African Americans has Sickle Cell trait. A simple blood test can differentiate between the trait and the disease. All hemoglobinopathies can be identified using hemoglobin electrophoresis, e.g. the separation of particles into “bands” in an electrical field to separate the different varieties of hemoglobinopathies. Most states test newborn babies as part of their newborn screening programs (NIH 2010).

Why Sickle Cell Anemia: The Malaria Connection

The reason Sickle cell disease has become a poster child for the ToE is due to the fact that in countries endemic for malaria, people who carry only one of the two alleles for sickle cell disease are said to have only the trait. These individuals do not go on to develop the more serious complications of the disease. It has been demonstrated that those people with sickle cell trait have an increased resistance to malaria. In certain parts of the world, malaria is a very serious problem having a decidedly adverse impact on the mortality and morbidity of the populations affected.

Malaria is a mosquito-borne infectious disease caused by the eukaryotic protist of the genus Plasmodium. It is widespread in tropical and subtropical regions, including parts of the Americas (22 countries), Asia, and Africa. Each year, there are approximately 35—500 million cases of malaria worldwide, killing between one and three million people, the majority of whom are young children in sub-Saharan Africa. Malaria is commonly associated with poverty, but is also a cause of poverty (Golin & Zimmermann 2007) and a major hindrance to economic development.

ring-form_and_gametocytes_of_Plasmodium_falciparum

Malaria Parasite P. falciparum


Here are the stunning statistics concerning the adverse impact malaria has on people in Africa.

  • Nearly one million people die from malaria each year, mostly children younger than five years old.
  • There are an estimated 250 million cases of malaria each year.
  • Although the vast majority of malaria cases occur in sub-Saharan Africa, the disease is a public-health problem in more than 109 countries in the world, 45 of which are in Africa.
  • Approximately 3.3 billion people live in areas where malaria is a constant threat.
  • 90% of all malaria deaths occur in sub-Saharan Africa.
  • Malaria costs an estimated $12 billion in lost productivity in Africa.
  • When insecticide-treated nets are used properly by three-quarters of the people in a community, malaria transmission is cut by 50%, child deaths are cut by 20%, and the mosquito population drops by as much as 90%.
  • It is estimated that less than 5% of children in sub-Saharan Africa currently sleep under any type of insecticide-treated net (Nets for Life 2010).

According to the World Health Organization (WHO) in 2008, there were 247 million cases of malaria and nearly one million deaths – mostly among children living in Africa. In Africa a child dies every 45 seconds of Malaria, the disease accounts for 20% of all childhood deaths (WHO 2010).

The fact that some benefit can be seen in certain genetic mutations is not always supportive of Darwinian Theory. This is because Darwinian evolution requires new information to be generated in order to produce the types of major changes postulated by the ToE, e.g. every increasing complexity in an upward move from microbes to men.   

Are those with Sickle Cell trait really safe?

The fact that Sickle Cell trait may offer some immunity to infection from the  malaria parasite does not negate the overwhelming evidence that in Sub-Saharan Africa, as many as 2 percent of babies are born with SCD will die in infancy. Up to 25 percent of the people in these areas are believed to carry the sickle cell trait and will infect 25% of their children with this deadly disease.

A study in the New England Journal of Medicine followed 3,764 patients from the USA. Conclusions were as follows: Fifty percent of patients with sickle cell anemia survived beyond the fifth decade. A large proportion of those who died had no overt chronic organ failure, but died during an acute episode of pain, chest syndrome, or stroke. Early mortality was highest among patients whose disease was symptomatic. A high level of fetal hemoglobin predicted improved survival and is probably a reliable childhood forecaster of adult life expectancy (Platt et al.1994).

This NEJM study was done on patients receiving the best medical care available at that time. The life expectancy in under-developed nations, e.g. Africa, is extremely low. One-third of all indigenes of sub-Saharan Africa carry the sickle cell gene, and approximately, 230,000 African children are born with sickle-cell disease each year. It can hardly be said that the certain death of a more than a quarter million children every year is evidence in support of the kinds of changes that can produce feet and hands from flippers or lungs from gills. In fact, natural selection is a scenario where on-going death and destruction leave only the fittest of life forms left standing. It takes an enormous leap of faith to postulate that a minor immunity to malaria can be an overall plus when so many are suffering the ravages of homozygous form of this disease. 

Sickle Cell Trait isn’t everything it’s cracked up to be

There is a certain amount of immunity from the malarial parasite for those with Sickle Cell trait, however, there is additional evidence that those with Sickle Cell trait can have serious medical consequences associated with this anomaly. There is convincing evidence that certain abnormalities do occur with increased frequency in the Sickle Cell trait. Among these are hyposthenuria, renal hematuria, bacteriuria and pyelonephritis in pregnancy, and splenic infarction with high altitude hypoxia. Other real hazards may exist for the person with sickle cell trait, but these await convincing demonstration by properly controlled studies (Sears 1978).

Although there are some studies that disagree with the conclusions of Dr. Sears, such as the 1982 update on this subject by Lenworth Johnson (Johnson 1982), a more recent evaluation can be found supporting Dr. Sear’s results on the Harvard University’s School of Medicine website. In this 2000 study by John Kark, M.D., formerly of the Uniformed Services University of Health Sciences at Bethesda, MD., and currently a professor of hematology at the Howard University School of Medicine’s Center for Sickle Cell disease, the following was reported: Sickle cell trait usually is not regarded as a disease state because it has complications that are either uncommon or mild. Nevertheless, under unusual circumstances serious morbidity or mortality can result from complications related to polymerization of deoxy-hemoglobin S. Such problems include increased urinary tract infection in women, gross hematuria, complications of hyphema, splenic infarction with altitude hypoxia or exercise, and life-threatening complications of exercise, exertional heat illness (exertional rhabdomyolysis, heat stroke, or renal failure) or idiopathic sudden death. Pathologic processes that cause hypoxia, acidosis, dehydration, hyperosmolality, hypothermia, or elevated erythrocyte 2,3-DPG can transform silent sickle cell trait into a syndrome resembling sickle cell disease with vaso-occlusion due to rigid erythrocytes. Compound heterozygous sickle cell disease can be mistaken as uncomplicated sickle cell trait, particularly when an unusual globin variant is involved (Kark 2000).

More recently, the medical community has been recommending that those patients who present with Sickle Cell trait be given anti-malarial medications. They explain that a person with Sickle Cell trait should still take malaria protection. It will not stop an infection. It may make it less invasive (SCIC 2010).

My own secular training was in the field of clinical laboratory science. I have seen first hand the devastation of this disease. I was a young medical technology student when we were told to start testing all neonates of Hispanic descent for Sickle Cell anemia. We had previously only routinely screened black children for this disease, and we were now being advised to expand our testing.

It was during my clinical rotation in medical technology at Peninsula Hospital Center in Far Rockaway, NY that I observed a patient who was homozygous for this disease slip into Sickle Cell crisis. She was a frequent patient in our hospital requiring numerous hospitalizations and frequent transfusions to combat the complications of being homozygous for SCD. Patients who are homozygous (Hgb. SS) can go into a life-threatening condition called “sickle cell crisis” at any time.  If those who are infected do not have access to the highest standard of medical care, they will die before reaching puberty. Those who are in developed nations can be treated; however, their life expectancy is far less than those without the disease. Men with sickle cell disease live for about 42 years, on average. For women, the average is 48 years. All of them are at increased risk for infection, stroke, and blindness.  

Resistance to Malaria is not a direct result of Darwinian mechanisms

Imagine the surprise when researchers point out that the hemoglobin S (Hgb. AS) mutation that offers some protection against malaria did not develop as a direct response to the malarial parasite. It occurred by chance (emphasis added). Those people without the mutation, living in areas endemic for malaria, were at an increased risk to contract the malarial parasite and develop this infections disease. They would exhibit symptoms of high fevers, headache, muscle pain, enlarged spleen, and anemia. People carrying only two Hgb. AA (non-Sickle Cell) genes often died in their first year of life when infected with malaria. Those who were lucky enough to carry the Hgb. AS gene when malaria struck had a better chance of living. They would survive to produce children and their Hgb. AS-carrying children in turn would have more Hgb. AS-carrying children (SCIC 2010).

Of course this rosy picture of bolstered immunity due to having only the trait for Sickle Cell anemia makes no mention of the increased incidence of spreading the actual disease, and the certainty of early death, in this same population. Parents who are both carriers of the trait would have a 25% probability of passing this lethal form of SCD to their offspring.

Those who attempt to use this particular genetic mutation to support the Theory of Evolution are choosing a relatively poor example. Although random mutations do occur in nature, occasionally offering some positive benefit for the organism in which the mutation occurs, these instances fall short of providing convincing evidence for macroevolution. They utterly fail to produce the major changes required by the ToE, because they produce no new genetic information. In fact, these mutations are often the result of a “loss” of genetic information and are, therefore, incapable of producing any real transformative change. Microevolution, or changes within kind as the Bible defines it, or speciation in evolutionary terms, is not evidence of the major changes that need to occur in support of Darwinian Theory, e.g. macroevolution.

The Sickle Cell example fails to provide convincing evidence of macroevolution, the major tenet of Darwinian Theory. Small horizontal changes along the evolutionary plane are not evidence of the major vertical changes that need to occur in support of Darwin’s Theory. They are examples of adaptation, not evolution. Adaptation is an ability pre-programmed into our genes by the Creator. He is the master Designer who, in the beginning, ordained that all living organisms should “be fruitful and multiply.”

In their zeal to find support for the ToE, evolutionists use examples like SCD to support a theory that all living things are related to one another, and the changes that occur can be explained by natural selection and the rare beneficial mutation. When this example is promoted, the facts concerning this particular disease do not really support macroevolution at all. While those who inherit the trait for SCD are more resistant to malaria, the consequences of this particular mutation are in fact an example of adaptation via a random accident resulting in a loss of genetic information, and not Darwinian Evolution.

Steven Rowitt, Th.M., Ph.D.(c)
Chief Technical Advisor
Creation Studies Institute

Dig Deeper: Recommended Resources

Johnson, Lenworth (1982). Sickle Cell Trait: An Update. J Natl Med Assoc. 1982 August; 74(8):
          751–757.  Accessed 13:25 on 5/6/10 at http://www.ncbi.nlm.nih.gov/pmc/articles/PMC
          2552960/.

Kark, John (2000). Sickle Cell Trait. Accessed 13:40 on 5/6/10 at http://sickle.bwh.harvard.edu/
          sickle_trait.html.

Nets for Life (2010). A Partnership for Malaria Prevention in Africa. Accessed 12:40 on 5/6/10
          at http://www.netsforlifeafrica.org/malaria/malaria-statistics.

NIH (2010). National Institute of Health. Medline Plus. Sickle Cell Anemia. Accessed 12:20 on
          5/6/10 at http://www.nlm.nih.gov/medlineplus/sicklecellanemia.html.

Platt, O.S., Brambilla, D.J., Rosse, W.F., Milner, P.F., Castro, O., Steinberg, M.H., Klug, P.P.
          (1994). N Engl J Med. 1994 Jun 9;330(23):1639-44. Accessed 14:15 on 5/5/10 at
          http://content.nejm.org/cgi/content/short/330/23/1639.

SCIC (2010). The Sickle Cell Information Center. Emory University School of Medicine.
          How did the HbS mutation evolve and why it persists today among certain populations?
          Accessed 13:45 on 5/6/10 at http://www.scinfo.org/faqtrait.htm.
SCIC (2010). The genesis of sickle cell. Ibid.

Sears, David A. (1978). The morbidity of sickle cell trait: A review of the literature. Am J Med.  
          Volume 64, Issue 6, Pages 1021-1036.   

Snow, R. W., Guerra, C.A., Noor, A.M., Myint, H.Y., Hay, S.I. (2005). The global distribution
          of clinical episodes of Plasmodium falciparum malaria, Nature 434 (7030): 214-7.
          Dio:10.1038/nature03342. PMID 15759000.

U.S. Library of Medicine (2007). Genetics Home Reference. Sickle Cell Disease. Accessed
          12:10 on 5/6/10 at http://ghr.nlm.nih.gov/condition=sicklecelldisease.

WHO (2010). World Health Organization. Fact sheet No. 94. Accessed 13:00 on 5/5/10 at
          http://www.who.int/mediacentre/factsheets/fs094/en/index.html


 
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