[Anaemia caused by a congenital haemoglobin defect can also occur in native Dutch patients]

An 11-year-old boy of Dutch descent had suffered from tiredness, pallor and poor appetite for many years. There was no indication of chronic infection. Iron supplements did not produce sufficient improvement in the symptoms. Following analysis using fast protein liquid chromatography and DNA sequencing analysis, it appeared that this was a case of β-thalassaemia intermedia, caused by a point mutation in the promotor region of the β-globulin gene. The boy's parents both proved to be heterozygotes for this point mutation. A second patient, a 5-year-old girl of Dutch descent, suffered from an icterus following a respiratory tract infection. Splenomegaly, hyperbilirubinaemia and microcytic anaemia with raised reticulocyte values were observed. Because of the presence of spherocytes, hereditary spherocytosis was initially suspected. On further analysis Heinz bodies were also seen, following which DNA sequencing analysis showed a de novo Hb Köln mutation. Congenital haemoglobin defects are usually associated with people originating from Africa, the Mediterranean, the Middle-East or South-East Asia. That such abnormalities can also occur in children of Dutch descent is demonstrated by these two cases.