We used the most recent data from NFHS-4 (2015–2016), merged with the previous NFHS-3 survey (2005–2006), to comprehensively examine the changes in Hb and anaemia after a 10-year gap at both national and state levels, as well as for different age groups and target populations (children, pregnant women and non-pregnant women). The gene discussed is GSTM1; the disease is anemia (phenotype).