GSTM1 and xanthoma: This study revealed that a child with xanthomas as the initial symptom, along with Chol ≤ 15.41 mmol/L, LDL-c ≤ 13.22 mmol/L, MPV ≥ 9.05 fl., or Hb ≤ 120 g/L could be clinically diagnosed as STSL.