Background: Alpha-thalassaemia is an autosomal recessive disorder characterized by defective production of the
alpha chain of haemoglobin. It is caused mainly by deletions of one or both of the duplicated alpha-globin genes
on chromosome 16, and/or by nucleotide variations, known as “nondeletion” mutations. Definition of the alpha
globin genotype in carriers supports genetic counselling, and in patients with Hb H disease is useful to predict
prognosis and management options. Here, we report a method that facilitates direct detection by naked eye of
the 13 most common “nondeletion” alpha-globin gene mutations in populations around the Mediterranean
and Middle East.
Methods and results: Themethod comprises (i) PCR amplification of a single 1087 bp fragment for each HBA1 and
HBA2 gene (separately); (ii)multiplex primer extension reaction of just 10 cycles, using unpurified amplification
product as a template, to incorporate biotin into those allele-specific primers that extend and, finally, (iii) visual
detection of the reaction products within minutes by the dipstick biosensor. The method was evaluated by
analysing 105 samples of known genotypes and the results were found fully concordant with those obtained
by the reference methods.
Conclusions: The proposed assay is particularly suited for small molecular-diagnostic laboratories with a limited
budget and a low-to-medium sample volume. In addition this platform represents a very simple and useful
genotyping tool to support gene scanning methods whenever nucleotide variations have to be specified.