Homozygosity for the delta-chain variant haemoglobin A2' (HbB2) (delta 16 Gly----Arg)

A healthy 20-year-old woman, belonging to the Kgalagadi tribe of Botswana, has been found to possess a variant Haemoglobin A2 as her only minor haemoglobin component. Fingerprinting and amino-acid analysis have shown that it is Haemoglobin A2' (delta 16 Gly----Arg). The one parent available for study is heterozygous for the Hb delta A2' 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 the Hb delta A2' allele. No haematological abnormalities were evident.