Answer to Hb Electrophoresis

While we do not have sequencing information for this patient, the data are most consistent with presence of Hb C and beta⁺-thal in cis on the same beta gene allele (HBB).

Considerations:

• Elevated HbA2 = beta thalassemia
• Hb C lower than expected for Hb C trait, possibly because its expression is being driven by a thalassemic allele
• Hb A > 50%, which would not occur if one beta allele was C (say mom’s), and the other was beta⁺-thal (dad’s).

I cannot find any similar examples in the literature, though there are a couple reports of beta⁺-thal in cis with the sickle gene (e.g., PMID: 2790205).