Hb Koya Dora [alpha142, Term-->Ser (TAA>TCA in alpha2)]: a rare mutation of the alpha2 gene stop codon associated with alpha-thalassemia.

Hb Constant Spring [(Hb CS) alpha142, Term-->Gln (TAA>CAA in alpha2)] and Hb Koya Dora [alpha142, Term-->Ser (TAA>TCA in alpha2)] both involve mutations of the alpha2 gene stop codon and while Hb CS is the most frequent cause of nondeletional alpha-thalassemia (alpha-thal) in Southeast Asia, Hb Koya Dora is limited to a restricted population from Andhra Pradesh, India. Here we identify a homozygous case of Hb Koya Dora and confirm the structure of the 31 residue alpha chain extension.