It's strange.Please can you send the figure of your HPLC report? Why have yu in the same pictogram the HbA1C?

Did you exclude any blood tranfusion in your patient? I suggest you to compare ypour HPLC data with another method like Capillary Electrophoresis or IEF.  

Best regards,

L.Tshilolo

Yes, Tsilolo, it is perplexing. Unfortunately, we have neither CE nor IEF methods available to compare. We've wanted to perform solubility test but thought the percentage HbS may be too little to give a positive result, but we'll do it notwithstanding. The person has no history of blood transfusion. The HbA1c percentage appears not high enough to diagnose diabetes. I'll try to scan and upload the graph here. Many thanks for your suggestions.

 Many thanks,Ramesh, for that suggestion. We had repeated the test when we saw the first results but that was immediately after the first run and not after we had ran a normal sample. I think it's a brilliant suggestion you've given and we'll definitely give it a try before we allude it to other reasons. I'll surely give you a feedback of the outcome of the repeat run of the sample.

Many thanks and best wishes,

Aminu.

Ramesh, the red cell indices are all normal and there is nothing in the peripheral blood film examination suggestive of a thalassaemia trait in this particular case. Delta-beta thalassemia are not common in our region according to the text books, although there are very few studies that characterised thalassaemic mutations in the local population. The subject here has no transfusion either recently nor in the past. We'd wanted to perform solubility test but thought the percentage HbS may be too little to give a positive result, so it is quite interesting to know that cellulose acetate electrophoresis can detect HbS this low. But our best bet is to re-run the sample after running a HbAA sample as you suggested.

That's a very interesting and insightful perspective, Ramesh!! It's all now beginning to make sense to me. How would you suggest to best confirm these two differential diagnoses? By PCR-RFLP or by direct sequencing of the beta-globin gene for the specific deletions? We don't have the facilities in my centre, but we can arrange to take the sample to where it can be done. Still, we're "forgetting" the S-window "for the time being", though. Remember? :)

Dear Ramesh,

Thank you very for the materials you have supplied above. They are very helpful.

I wish to let you know that the advice you gave so far have also proved extremely helpful in solving our interpretative problems. That we have repeated the HPLC of that person after running a HbAA sample, and to our astonishment, the S-window has disappeared! And all the other haemoglobin percentages including the HbF have remained largely the same! It is quite interesting how simple but logical modifications to procedures can bail you out in times of great uncertainties!

Now taking all the results of haematological analyses together, it appears the most likely diagnosis is heterozygous HPFH (HPFH trait) since the Hb concentration, the red cell count and the red cell indices are all normal. We will nevertheless go ahead and do the parental studies and DNA analysis to confirm the deletions, just to satisfy our curiosity. It is quite possible these deletional mutations are common in our environment, but lack of the appropriate investigative facilities hinder their detection and characterisation.

Once more, thank you very much Ramesh for the help you rendered.

Best wishes.

I will not go into the discussion on the data which has been done extensively above.The answer to the initial question is yes: there is at least one reported exemple of a b+-thal mutation (nt -88 C>T = HBB:c.-138C>T) in cis from the b-S mutation in a Moroccan woman. HbS was 11%, HbA2>6% and there was a clear microcytosis.

Baklouti et al. Beta+-thalassemia in cis of a sickle cell gene: occurrence of a promoter mutation on a beta s chromosome. Blood. 1989;74(5):1817-22.

Many thanks, Jacques, for the reference above. With this reference, at least we now know that this double mutation on the beta globin gene is not impossible in humans, though may be extremely rare. Although from the information given by Ramesh above on delta-beta thalassemia and the case you have provided, the two conditions could easily be confused because both scenarios have lower HbS than would be expected for a straight-forward sickle cell trait and microcytosis. The only possible difference might be the high HbF and low HbA2 in the delta-beta thal, and the high HbA2 (>6%) in the case you suggested above. I have gone through the paper by Baklouti et al but did not see reference to HbF level in that particular case, any idea if the level is also increased there?

Kind regards,

 real good interchange ! being a clinician, i take the option of sending the contact osf my lab "savers" : Lucinda Nóbrega ( HFF - Lisboa) , Armandina Miranda ( INDRJ - Lisboa)