Pyridoxal-5-phosphate-resistant sideroblastic anaemia with trisomy 8 mosaicism in the bone marrow.

A patient with sideroblastic anaemia manifested a trisomic condition for chromosome number 8 in 75% of his bone marrow cells. Cytogenetic studies of peripheral lymphocytes demonstrated a normal male karyotype. The anaemia was resistant to treatment with pyridoxal-5-phosphate; this is in contradiction with the response achieved in some patients with the primary acquired form of sideroblastic anaemia.