THE challenge of sickle cell disorder has confronted persons born with it over the years, with its traumatic and life threatening painful conditions. However, Dr. Olufunto Kalejaiye, a consultant haematologist at Lagos University Teaching Hospital (LUTH) dissects the issue of and how to care for the disease.
Dr. Kalejaiye explains that sickle cell disease/disorder (SCD) is a group of genetic disorders resulting from the presence of a mutated form of hemoglobin, a component of blood, hemoglobin S. (HbS). HbS arises from the substitution of valine for glutamic acid as the sixth amino acid of the beta globin chain. The resulting haemoglobin has the physical properties of forming polymers under deoxy or hypoxic conditions and also exhibits changes in solubility and molecular stability. These properties are responsible for the profound clinical expressions of the sickling syndromes.
“The polymer assumes the form of an elongated rope-like fibre, which usually aligns with other fibres, resulting in distortion into the classic crescent or sickle shape, which are unable to traverse capillaries easily causing ischemia and infarction of tissues supplied by these vessels. The life span of these sickled cells is shortened from about 120 days to 10-30 days, hence the chronic haemolysis that also characterises these disorders. Sickle cell disorder comprises the inheritance of the abnormal haemoglobin S with another abnormal haemoglobin.”
She continues, “The clinically important genotypes referred to as sickle cell disorder are HbSS (in which there is homozygosity for the mutation that causes HbS, that is, a person has two copies of the mutation that causes HbS and is termed sickle cell anaemia), HbSC sickle haemoglobin C disorder, HbSB+ thal (sickle cell beta plus thalassemia) and HbS/β0 (sickle beta-zero-thalassaemia). HbSC, HbSB+Thal and HbS/β0 are heterozygous states in which the person has only one copy of the mutation that causes HbS and one copy of another abnormal haemoglobin allele. Of all these, the homozygous HbS disease (HbSS), is the most common form of SCD and has been found to be the most troublesome in terms of severity of clinical manifestations.”
She stated that the clinical features of sickle cell disease are diverse. “Dactylitis (inflammatory swelling and tenderness of the bones affecting the hands and feet) is one of the early features and usually occurs between the ages of six months and five years.
Other features include subnormal growth and development from early childhood, frontal bossing, gnatopathy due to expansion of the medullary cavities in response to chronic haemolysis, pallor and jaundice (yellowing of the eyes consequent upon hemolysis , abdominal swelling consequent upon the liver (and spleen) macrophages overburdening with products of broken down red cells.”
However, usually by the age of eight years, the spleen is usually not enlarged in sickle cell anaemia due to auto-splenectomy from repeated infarctions of the spleen. The absence of the spleen predisposes to various infections particularly those caused by encapsulated organisms.
The presence of gall stones may or not be symptomatic- may rarely cause pain, infection or obstructive jaundice. People with sickle cell anemia may have long, thin limbs, and appear small for age. Puberty may also be delayed. Chronic leg ulceration is also a relatively common feature of sickle cell anaemia (though not commonly found below the age of 10 years) is as a result of various factors including mechanical obstruction by dense sickled cells, anaemia with reduced oxygen carrying capacity, and artero-venous shunting, which deprives the skin of oxygen.
The ulcers commonly occur around the medial and lateral malleoli (around the ankle) and can occur spontaneously or following trauma and can become infected, says Kalejaiye.