HBB and beta thalassemia: Notably, these variants do not completely abolish HBB transcription, and consequently, individuals harboring these variants in trans with HBB LOF variants often still produce adult hemoglobin (HbA), resulting in a milder form of beta-thalassemia (i.e., beta-thalassemia intermedia) compared to individuals with biallelic HBB LOF coding variants (Ropero et al. 2017).