A healthy 20-year-old woman, belonging to the Kgalagadi tribe of Botswana, has been found to possess a variant Haemoglobin A2as her only minor haemoglobin component. Fingerprinting and amino-acid analysis have shown that it is Haemoglobin A2′(δ16 Gly→Arg). The one parent available for study is heterozygous for theHbδA2′allele and the variant haemoglobin accounts for 3% of the total haemoglobin in the proband. It is reasoned that the proband is, therefore, homozygous for theHbδA2′allele. No haematological abnormalities were evident.