Beta thalassemia major, B0/B0 (two gene mutations, deletions or combination) results in very few to no beta chains being produced.
Hemoglobin A levels are at or near 0%.
(drawing modified from Harmening, 1999)
Other genotypes of beta thalassemia major not depicted include B0/B+ (one beta chain deleted, one partially deleted) and B+/B+ (both beta chain genes partially deleted).
