GSTM1 and anemia (phenotype): Calvo-Río et al. [7], compared their 417 patients and a series of children and adults with IgA vasculitis (HSP), they found 8.9% of anemia (Hb < 110 g/L) in their cases, compared to three of six studies that also found anemia, 2.3% in 87 patients, 7.7% in 104 and 1.6% in 61 patients.