Abstract

A family study is reported in which all three siblings were shown to be doubly heterozygous for haemoglobin D Los Angeles and beta thalassaemia, which resulted in a complete suppression of haemoglobin A synthesis. This demonstrates the effects of genetic interaction which occur when the genes for haemoglobin D Los Angeles and beta thalassaemia are both transmitted to the offspring. The importance of family studies in the investigation of haemoglobin abnormalities is stressed.