Authors' response to Dong-Zhi Li's letter: ‘Routine molecular screening for common ±-Thalassaemia deletions is necessary as part of an antenatal screening programme’

We thank Dr Li for his comments. Screening for a thalassaemia remains a difficult issue without a perfect solution. The aim of our research was primarily to assess the National Health Service (NHS) sickle and thalassaemia programme recommendation on screening for pregnancies at risk of Bart's hydrops. Such events are very unusual in the UK population as opposed to the considerably higher risk in southern China. Secondly, we wished to assess the type and prevalence of α globin deletions seen within our local population hence the application of universal α deletion screening for patients with low Mean Corpuscular Haemoglobin (MCH) regardless of partner testing. We accept that there may be more cost efficient strategies.

In fact, the ‘at risk ethnic origin/low MCH’ NHS screening programme approach is very similar to that adopted by Dr Li. Pregnant patients from an at-risk ethnic group with low MCH undergo partner testing as a first step. If the couple are both deemed to be at risk of carrying α⁰ thalassaemia then they will undergo multiplex PCR testing for α⁰ deletions.

Regarding the second point of double heterozygotes for α and β thalassaemia; although we did not clearly state this within the paper, we can confirm that it is the practice of the authors and the NHS sickle and thalassaemia screening programme to look for ‘silent’ α⁰ deletions in individuals with ²-thalassaemia trait in at risk ethnic groups.

Of course no available strategy takes into account mutational forms of alpha thalassaemia, which may interact with α⁰ deletions to cause fetal hydrops.