Sickle Cell Disease is a disabling condition that creeps on you unawares. Yet it is also one of the world’s commonest genetic disorders. The earlier the detection the easier it will be to manage the disease for which there is yet no cure and is irreversible. Added to this is the new risk of the Covid-19 virus which could expose persons with sickle cell disease to further health complications.
The Sunday Observer spoke to Senior Consultant Hematologist, National Hospital, Colombo, Dr. Bhaddika Jayaratne to find out what this little understood disease is all about, how it is diagnosed and investigations by the Sri Lanka College of Hematologists to raise more awareness.
Excerpts…
Q. On June 19 the world observed the tenth anniversary of World Sickle Cell Day. Although Sickle Cell Disease (SCD) is recognised as one of the world’s foremost genetic diseases, many persons don’t know what the disease is while even those with this condition remain unaware they have it. Explain what it is.
A. SCD is a group of inherited genetic red blood cell disorders. Healthy red cells are biconcave in shape and circulate through minute blood vessels or capillaries easily carrying hemoglobin bound oxygen from the lungs to peripheral tissues.
In people who have SCD, the red cells become harder and crescentic or sickle shape due to the presence of a mutated hemoglobin gene ‘HbS’.
These abnormal red cells are called sickle cells. They constantly lack capacity to bind oxygen, breakdown prematually and tend to clog the blood flow particularly in the small blood vessels giving rise to multiple clinical complications of varying degrees of severity.
Q. How many cases have been reported here?
A. Only about 2.8 % sickle cell patients were accounted out of all the other inherited abnormal hemoglobin diseases (hemoglobinopathies) at an island wide survey done recently, mostly in coastal areas which shows (HbS) is uncommon here.
Q. How is it transmitted?
A. The disease is transmitted in autosomal recessive pattern. As these genes are not linked to the sex chromosomes both parents can transmit the disease to the children equally.
Q. What are the chances of someone with HbS who marries a person with similar traits to have a normal baby?
A. If both parents carry one copy of HbS gene, the chances of getting an affected or unaffected pregnancy is 25 %. There is a 50 % chance of getting an asymptomatic carrier state in this kind of example.
Q. Traits that help recognise SCD?
A. Those who inherit two sickle genes from each parent get ‘HbSS’ or the homozygous sickle cell disease which is the most severe form of the disease. Those who inherit one sickle gene from one parent and a normal hemoglobin ‘A’ gene from the other parent, get ‘HbAS’ called sickle cell trait (SCT).
People with SCT do not manifest any symptoms and live a normal life. But they transmit the SCT to their children. Those who inherit HbS gene from one parent and HbC from the other parent get HbSC disease. This is usually a milder form of SCD. Those who inherit HbS gene from one parent and Beta thalassaemia gene from the other parent get HbS Beta thal (SBT). The severity of this form depends on the severity of the beta Thalassaemia gene.
Q. What are the impacts on the body?
A. Patients present with symptoms and signs of excessive breakdown of red cells in the vasculature resulting in low hemoglobin level or anemia. If anemia is severe there could be shortness of breath and may feel their own heartbeat. They also could show yellow discoloration of eyes and urine. The complications could be severe and acute due to the lack of supply of oxygen to tissues or obstruction to the blood flow particularly in small vessels resulting in damage to organs and episodes of pain usually in the chest, abdomen, joints and bones.
Persistent high blood pressure in the local vasculature of the lungs results in a condition called pulmonary hypertension which could lead to heart failure and even fatal outcome. Clogging blood flow in the minute arteries of the brain results in stroke or transient ischemic attack. If the small blood vessels to eye is affected, vision impairment or blindness could happen.
Q. Any other complications?
A. Chronic damage to liver, kidneys and pancreas can give rise to liver-renal failure and diabetes mellitus. Sickle patients also have a higher chance of experiencing deep vein thrombosis and pulmonary embolism which could result in death.
Encapsulated bacterial infections such as pneumococcal pneumonia is common in them precipitating acute complications. Recurrent infections and pain can lead to malnutrition and growth retardation in children.
Q. Today these people also live amid the Covid-19 outbreak. How vulnerable are they to getting the disease?
A. There are no data, but patients with SCD are at a higher risk of getting any infection due to immune compromised states induced by defective activity of the compliment pathway and atrophied spleen. The consequences of the Covid-19 infection could be very serious in them when infection and high fever trigger acute severe complications of the sickle disease or when breakdown of red cells in excess takes place.
Covid-19 is primarily an infection that affects the respiratory system which could aggravate the hypoxic situation in them by further reducing oxygen to tissues. This kind of acute severe hypoxia could affect any vital organ including infarctions to heart and brain or death. Covid-19 could also manifest critically in patients with SCD due to underlying organ damage and coexisting morbidities such as diabetes mellitus, heart failure or high blood pressure in the lung vessels.
Q. Main challenges you face in getting patients with this condition to seek treatment?
A. One problem is detecting a carrier who is asymptomatic often at family screening done for another member of his or her family or at premarital partner screening. It is important that the patient is clinically diagnosed and managed appropriately, under supervision of the hematology team in most of the public sector hospitals. However, the process of patient management as a whole, is a teamwork with pediatricians, surgeons, blood transfusion physicians and other physicians.
Q. Tests that indicate SCD?
A. From the patient’s point of view, drawing a simple venous sample of blood, and tests can be done at any age. The sickle hemoglobin should be confirmed by two methods of tests. The confirmation of the disease depends on the demonstration of HbS, HbF and HbA2 in blood. The tests that are used to detect them are hemoglobin electrophoresis, capillary electrophoresis and high performance liquid chromatography. The sickling test is a simple slide test that is used mainly for the purpose of screening the disease.
Q. Are there screening programs for SCD in Sri Lanka to detect the disease early?
A. There are no screening programs for SCD in Sri Lanka.
Q. Why?
A. I think this has not been an issue in the field yet, due to the low prevalence of the disease in the country. However, the facility for family screening and premarital screening is available at hematology units of main hospitals, for anyone suspected of the disease.
Q. How are these patients managed?
A. The patients with sickle disease are followed up at special hematology clinics of main hospitals and those who present with complications are managed in wards and emergency units according to the severity of their symptoms.
These facilities are readily available in public and private sector hospitals. Pain killers, treatment with oxygen, adequate hydration, treating acute infections and prophylaxis including appropriate vaccinations and simple blood transfusions to exchange transfusions are the mainstay of management of these patients with complications.
Q. How far has new technology helped in improving survival rates and life expectancy in patients?
A. With the use of a drug called hydroxyurea the survival rate and life expectancy of patients with SCD has remarkably improved over the years. The cure of the disease can only be achieved by successful stem cell transplantation.
Suitable candidates are usually children below 16 years with minimal organ damage and who have matched donors.
Q. What is the Sri Lanka College of Hematologists (SLCH) doing to educate more people starting from community level upwards on SCD?
A. At present there are about 81 members in the College of Hematologists who serve island wide as consultant hematologists or academics and administratively as heads of the hematology units in teaching and general hospitals and hematology departments in the universities.
They conduct special hematology clinics at their institutions where improvement of the quality of life of patients and health education are focused. The diagnosis of the disease and management of acute complications in the wards are led by the hematologists including blood transfusions.
They are also involved in family screening and pre-marital partner screening. Pre-marital and pregnancy counselling is done at their clinics whenever the need arises while maintaining an institutional database.
Hematologists are also involved in the National thalassaemia screening program in which, HbS can be detected while the College also participated in discussions regarding stipulating guidelines for Covid-19 infection at the initial stages of the pandemic.
Q. Your message to patients with SCD amid the Covid-19 pandemic?
A. If you are diagnosed with sickle disease, even asymptomatic, it is important to be aware and knowledgeable about the condition in order to live a quality life physically, intellectually, emotionally, and socially.
It is important to avoid any risk situations and never disregard medical advice, follow regular clinics and show a good compliance on taking long term antibiotics, folic acid, the drug hydroxyurea and vaccinations that help in preventing episodes of pain.
Do not delay to seek medical care when you are ill. If you have a family member or are at any suspicion of the disease, reach hematology services available at main public hospitals or in the private sector for family screening or pre-marital partner screening and necessary counselling.
Living in the era of Covid-19 pandemic, it is important that people with sickle disease take extra precautions against the viral infection, strictly following guidelines and protocols. Do not hesitate to seek immediate medical advice in a case of any febrile illness.