United by gene, divided by blood

Just 100 kms away from Mumbai lives a tribal family in the grip of dreaded sickle cell disease (SCD) or sickle cell anemia. Sugana (belonging to the Warli tribe) had been suffering from this disease for a long time, but was diagnosed only last year at a health camp. Her daughter Rani (6), too, suffers from the disease, while her year-old son, Raja, is yet to be tested. All she knows about the disease is that it is a serious blood disorder, typically inherited from the patient’s parents.

India has the highest number of sickle cell gene carriers in the world, accounting to more than 50 per cent globally. According to Indian Council of Medical Research, 20 per cent of children with sickle cell disease die by the age of two and 30 per cent of children with this disease (in tribal community) die before they reach adulthood.

Sickle Cell anaemia
It is a genetic disorder resulting from inheritance of abnormal haemoglobin genes from both parents. Red blood cells (RBC) with normal haemoglobin are generally round. In SCD patients, the haemoglobin  molecules are abnormal, which make their RBC sickle- or crescent-shaped. These RBC die prematurely, which can lead to anaemia. Further, the abnormal RBC gets stuck in small blood vessels, slowing down the passage of blood and oxygen, leading to severe pain,jaundice, anaemia and recurrent infections.

A person having two copies of the abnormal gene has SCD, while a person having only one copy of the abnormal gene is said to be a carrier (sickle cell trait). Carriers don’t have the disease, but can pass the defective gene to their children.

Sharing an insight on SCD, Dr Sheetal Sharda, clinical geneticist at a genomics-based diagnostics and research company in Bengaluru, says, “This disease is mainly associated with malaria-endemic areas and African lineage. SCD has significant implications such as higher morbidity and mortality, poor quality of life and lower life expectancy. Of 18 crore tribal population, approximately 1.80 crore people are carriers of SCD, while 14 lakh people suffer from it.”

The only cure for SCD is bone marrow transplantation. In this procedure, the patient is transplanted with bone marrow from healthy, genetically compatible sibling donors. However, only less than 20 per cent of children with this disease have a healthy, matched sibling donor. Gene therapy promises a cure, but is still in experimental stages.

In India, newborn screening programmes for SCD among tribal and non-tribal populations have only recently been initiated during the last three-five years in south Gujarat, Maharashtra, Chhattisgarh, Odisha and Madhya Pradesh. In case of newborns detected with SCD, the disease may express its severity only after a particular age and a timely course of medication and vaccines.

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