HBSC disease or sickle-cell disease, (also known as sickle-cell anaemia, siclemia, or drepanocytosis), is a life-long hemoglobinopathy characterized bya biochemical lesion consisting in the replacement of the glutamic acid from the sixth position of the beta chain of hemoglobin with valin, resulting a new type of hemoglobin, with new properties, and so, the red blood cells will have an abnormal, sickle shape. This form has as a consequence a decreased cell flexibility and a risk of various complications. The life expectancy in people with siclemia is shortened, and the studies performed have reported an average life expectancy of 42 years for men and 48 years for women. The disease is determined by a mutation in the hemoglobin gene.

The symptoms of HbSC disease (or sickle-cell disease) depend on whether the patient is homozygot for the mutated gene or not.

The heterozygotic form is usually asymptomatic , the carriers being accidentally discovered on the ocasion of medical investigations for other conditions. There should be known that in some situations such as diving or general anaesthesia thrombosis may occur, leading to infarction affecting virtually any organ.

The homozygotic form has the signs and symptoms determined by two causes: hemolysis and occlusion.

The hemolysis determines the chronic hemolytic anemia which is responsible of the aspect of the characteristic aspec of the children with HbSC disease: short body, long legs and arms, lumbar lordosis and cranial abnormalities. The jaundica is variable, depending on the degree of hemolysis. The spleen does not develop normally due to the reccurent infarctions and in adult life the atrophy and fibrosis will lead to a condition called autosplenectomy.

Almost 30% of the patients will also develop pigmentary gallstones. In these cases the cholecistectomy ia not indicated, unless the colic pain occurs.  The differential diagnosis in this case must be made between the pain produced by acute cholecystitis and the pain from cholelithiasis determined by siclemia.

Splenomegaly may occur if the HbSC disease is associated with other blood disorders.

The occlusion ofthe blood vessels may affect any organ or tissue, leading to infarction. The vaso-occlusive crisis is determined by the sickle-shaped red blood cells  obstructing the capillaries and restricting the blood flow to a tissue or organ, resulting in pain and ischemia leading to organ damage. The severity and duration of these crises vary considerably.

Another classic form of sickle crisis is the acute chest syndrome, a syndrome characterised by fever, dyspnea (shortness of breath) , chest pain and pulmonary infiltrate on a chest X ray. Given the fact  that pneumonia and sickling in the lung have all these symptoms the patient should be  treated for both conditions. This syndrome may be triggered by respiratory infections,  atelectasis, opiate administration, bone-marrow embolisation, or , possibly, by surgery.