The Spectrum of β-Thalassemia Mutations in the Population Migration in Lebanon: A 6-Year Retrospective Study.

β-Thalassemia (β-thal) is highly prevalent among the Mediterranean populations. In Lebanon, the carrier rate of the disease is estimated to be around 2.0-3.0%. In this retrospective study, we determined the spectrum of β-thal mutations in a total of 170 individuals from a sample of 140 Lebanese, Iraqi and Syrian refugee families in Lebanon, over a period from 2012 to 2018. Twenty-eight different β-globin gene mutations were identified. The most prevalent mutations were IVS-I-110 (G>A) (: c.93-21G>A), IVS-II-1 (G>A) (: c.315+1G>A), IVS-I-6 (T>C) (: c.92+6T>C) and IVS-I-1 (G>A) (: c.92+1G>A), accounting for the majority of mutations found in mutations analysed in 250 alleles. Ten different β-globin gene mutations that were not previously described in Lebanon were identified in our study. These mutations include the IVS-II-848 (C>A) (: c.316-3C>A), codons 9/10 (+T) (: c.30_31insT), codon 15 (-T) (: c.46delT), -86 (C>G) (: c.-136C>G), Cap +22 (G>A) (: c.-29G>A), -28 (A>C) (: c.-78A>C), codon 7 (AG>AG) (: c.22G>T), codon 26 (AG>AG) (: c.79G>T), codons 41/42 (-TTCT) (: c.126_129delCTTT), and codons 82/83 (-G) (: c.250delG). Of these, six mutations [codons 9/10, codon 15 (-T), -86, codon 7, codon 26, codons 82/83) were identified in Lebanese samples only; one mutation (IVS-II-848) was identified in both Lebanese and Iraqis; and three mutations (Cap +22, -28, codons 41/42) were identified in Iraqi samples only. Further studies will help better delineate the spectrum of β-thal mutations among different ethnic groups, and provide crucial prevention strategies.