A rare α-thalassemia deletion, -α27.6, is identified from three Chinese families in Fujian province.

Alpha (α)-thalassemia (thal) is a common single-gene genetic disease in southern China, which may cause Hb Bart's hydrops fetalis and Hb H disease. In α+ thal, one of the α genes is inactivated, due either to a deletion (-α) such as the rightward deletion (-α3.7) and leftward deletion (-α4.2), or to another form of mutation (αTα), such as the Hb Constant Spring (αCSα). In this study, three probands from three Chinese families in Fujian Province showed HbH disease traits, while their common genotypes of α-thal were --SEA/--SEA at a routine analysis. In doing so, we further found a rare 27.6 kb deletion on the α-globin gene cluster in the three probands by MLPA (multiplex ligation-dependent probe amplification) and Sanger DNA sequencing, and its breakpoints were detected to lie between coordinates 9079 and 36718 with a total of 27,640 nucleotides deletion. The accurate genotypes of the three probands were -α27.6/--SEA, which led to a very mild hemoglobin H (HbH) disease phenotype with low MCV, MCH, and HbA2 levels. Phenotypic analysis on the heterozygote of this deletion revealed it as α+ mutation. In conclusion, we report a rare α-thal deletion, -α27.6, in three Chinese families from Fujian Province. Our study extends the spectrum of the α-thal mutation in the Chinese population. It is necessary to increase awareness of the rare α-thal mutation and to increase its detection, which will prove valuable in genetic counseling and prenatal diagnosis in Fujian Province.