Wide spectrum of novel and rare hemoglobin variants in the multi-ethnic Indian population: A review.

The hemoglobin (Hb) variants are qualitative abnormalities due to production of structurally abnormal globin proteins. They are categorized based on the type of mutation present in the α1, α2, ß, Gγ, Aγ and δ globin genes. So far, more than 1550 Hb variants are reported in the database. They could lead to Hb polymerization, Hb instability, altered oxygen affinity and decreased oxygen-carrying capacity of Hb or have no clinical manifestations. In India, ethnic diversity, consanguinity, regional variations and migration result in the presence of different Hb variants. We have compiled all the variants of α, ß and δ globin chains in heterozygous, homozygous and in compound heterozygous forms reported from India in the last 52 years. Of the 63 rare and novel hemoglobin variants reported from India, 22 were α-globin chain variants, 37 were ß-globin chain variants and 4 were δ-globin chain variants. Twelve novel Hb variants (Hb J Rajappan, Hb Koya Dora, Hb Rampa, Hb Godavari, Hb Chandigarh, Hb D Agri, Hb Lucknow, Hb Vellore, Hb Midnapore, Hb Bijnor, Hb A2Tianhe and Hb A2Saurashtra) were identified among persons of Indian origin. Majority of them were picked up on HPLC. Some of the variants like Hb Titusville, Hb Shimonoseki, Hb Chandigarh, Hb D Agri, Hb Yaizu and Hb Vellore eluted in the HbS window whereas variants like HbD Iran, Hb St. Louis, Hb G Coushata, HbM Saskatoon, Hb Lucknow, Hb Grange-Blanche and Hb Tianshui showed falsely elevated HbA2. Hence, careful and systematic investigations are required to identify them.

Newborn Screening for Sickle Cell Disease Among Tribal Populations in the States of Gujarat and Madhya Pradesh in India: Evaluation and Outcome Over 6 Years.

Sickle cell disease (SCD) poses considerable public health problems in India. This study was undertaken to understand the clinical course of SCD among children identified during newborn screening programmes in Gujarat and Madhya Pradesh where the frequency of the HbS gene is high. A total of 8,916 newborn babies 8,411 from Gujarat and 505 from Madhya Pradesh were screened over 6 years (2010-2016) using HPLC and the diagnosis was confirmed by molecular analysis in a subset. A total of 128 babies (122 Gujarat, 6 Madhya Pradesh) were identified with sickle cell disease, of whom 87 (69 HbSS, 18 HbS-ß thalassemia) from Gujarat were followed for 0.5-6.6 years. Acute painful events, severe anemia and fever with infections were the major complications and 23 babies required hospitalization. Severe to moderate clinical presentation was found in 13.8% babies with SCD whereas, 86.2% babies had a milder presentation. Presence of ameliorating factors (α-thalassemia and Xmn 1 polymorphism) did not have a discernible effect on the clinical severity. Parents of babies with SCD were educated and counseled for home care. Distribution of mobile phones to 44 families having babies with SCD was beneficial as it allowed regular contact with patients and their families. Genetic counseling to the affected families has increased the awareness and acceptance for prenatal diagnosis and 18 couples opted for prenatal diagnosis in subsequent pregnancies. SCD is not always mild among tribal groups in India. Therefore, facilities for early diagnosis and prophylactic treatment in the tertiary care centers should be made available. The difficulties in regular follow up of the babies in remote rural areas have also been highlighted.