Inherited blood disorders: gene deletion causes blood disorders, prenatal diagnosis is the solution to the problem

By Syed Akbar
Hyderabad, Sept 2: Inherited blood disorders including thalassemias
and sickle cell anaemia in people in Andhra Pradesh are due to
deletion of certain genes and the problem could be averted through
prenatal diagnosis.

Researchers at the city-based Institute of Genetics and Hospital for
Genetic Diseases, Osmania University, have found the deletion of genes
(IVS1-5(G-C) and 619 bp) in people suffering from inherited blood
disorders or haemoglobinopathies in Andhra Pradesh. They analysed
about 1600 blood samples to arrive at the finding.

These blood disorders, which often prove fatal, are passed on from
parents to children and the risk rate is one out of four births.
Certain regions and communities living in India are prone to
haemoglobinopathies, particularly thalassemia. The frequency ranges
between one and 40 per cent in certain tribal populations in Andhra
Pradesh.

"Prenatal diagnosis at fourth or eighth week of pregnancy will tell us
whether a child is susceptible to an inherited blood disorder. Since
there's no treatment, prevention through prenatal diagnosis is the
best option. In such cases parents are advised to go in for medical
termination of pregnancy," said senior geneticist Dr MN Khaja.

Other congenital blood disorders linked to the deletion of IVS1-5
(G-C) and 619 bp genes are haemoglobin variants (people suffering from
the problem carry a variant form of haemoglobin), and hereditary
persistence of foetal haemoglobin. Normally foetal haemoglobin stops
at a certain stage leading to the formation of adult haemoglobin. But
in people suffering from this disorder, foetal haemoglobin continues
in the body even in the adult life,

Out of  about 1600 suspected blood samples studied by the IGHGD, the
researchers found 119 cases of beta-thalassemia major, and 347 cases
of beta-thalassemia trait. The samples also revealed incidence of
sickle cell anaemia, sickle cell trait, D-thalassemia, E-thalassemia,
double heterozygotes (mutations on two different genes). Molecular
analysis of the blood samples showed the presence of different
beta-thalassemia mutations in the State population.