Introduction Microcytic hypochromic anemia is a common he- matological abnormality in clinical practice and usually is caused by iron deficiency and â-thalassemia trait. Alpha-thalassemia should be considered when both these conditions are ex- cluded. The prevalence of 1–2 a-globin genes (a+ thalassemia) is variable, reaching over 80% in some tribal populations in India (Weatherall and Clegg 2001). The carrier rate of the b-thalassemia gene in India is 3–17% (Agarwal et al. 2000). Un- like b-thalassemia trait and iron deficiency, no simple biochemical test can detect a-thalassemia. There is a paucity of data on a genotyping in India. The prevalence of a-thalassemia based on Hb level in cord blood is estimated at 1–18%, de- pending on the methodology used (Desai et al. 1997). A high prevalence of deletion and non-deletion forms of a-thalassemia mutants was reported in a tribal population of Orissa in relation to sickle-cell diseases (Kulozik et al. 1988). Amulticentric study in a heterogeneous popula- tion shows a prevalence rate of 13%, with a major- ity showing -á 3.7 deletion (Ko et al. 1999). There is limited data reported in the literature for preva- lence of á-gene deletion in patients with microcytosis (Ko et al. 1999; Bergeron et al. 2005). Carriers of á-gene deletion have mild microcytosis with or without anemia. Although anemia is absent or unremarkable, it is important to diagnose á-thalassemia in order to diagnose the cause of microcytosis and to avoid repeated ex- pensive analysis and/or prolonged iron therapy. The co-existence of á-deletions in â-thalassemia patients modifies the phenotype. Thus in high-risk J Appl Genet 47(4), 2006, pp. 391–395 Short communication Genotyping of alpha-thalassemia in microcytic hypochromic anemia patients from North India Vaikam H. Sankar, Vandana Arya, Depshikha Tewari, Usha R. Gupta, Mandakini Pradhan, Sarita Agarwal Department of Genetics, Sanjay Gandhi Post-graduate Institute of Medical Sciences, Lucknow, India Abstract. Microcytic hypochromic anemia is a common condition in clinical practice and alpha-thalassemia has to be considered as a differential diagnosis. Molecular diagnosis of á-thalassemia is possible by polymerase chain reaction. The aim of this study was to evaluate the frequency of á-gene numbers in subjects with microcytosis. In total, 276 subjects with microcytic hypochromic anemia [MCV<80fl; MCH<27pg] were stud- ied. These include 125 with thalassemia trait, 48 with thalassemia major, 26 with sickle-cell thalassemia, 15 with E beta-thalassemia, 40 with iron-deficiency anemia, 8 with another hemolytic anemia, and 14 patients with no definite diagnosis. Genotyping for -á 3.7 deletion, -á 4.2 deletion, Hb Constant Spring, and á-triplications was done with polymerase chain reaction. The overall frequency of -á 3.7 deletion in 276 individuals is 12.7%. The calcu- lated allele frequency for á-thalassemia is 0.09. The subgroup analysis showed that co-inheritance of á-deletion is more frequent with the sickle-cell mutation than in other groups. We were able to diagnose 1/3 of unexplained cases of microcytosis as á-thalassemia carriers. The á-gene mutation is quite common in the Indian subcontinent. Molecular genotyping of á-thalassemia helps to diagnose unexplained microcytosis, and thus prevents unneces- sary iron supplementation. Key words: alpha 3.7 deletions, evaluation of anemia, microcytic hypochromic anemia, North India, single alpha-gene deletion. Received: May 19, 2006. Accepted: July 31, 2006. Correspondence: Sarita Agarwal, Department of Genetics, Sanjay Gandhi Post-graduate Institute of Medical Sciences, Lucknow, India. PIN: 226014; e-mail: saritaag@sancharnet.in, sarita@sgpgi.ac.in