[Analysis of the Types of Thalassemia Gene Mutations in Nanping Area of Fujian, China].

Objective: To investigation the types and frequencies of thalassemia gene mutations in pregnant population in Nanping area of Fujian Province, so as to provide a basis for prevention and control of birth children with moderate and severe thalassaemia in this area.

Methods: The genotyping of α and β thalassemia was performed using the gap-PCR (gap-PCR) technique combined with reverse dot blot (RDB). The genotyping test was performed by Gap-PCR for three rare deficient thalassemia. The cases with negative detection were further detected by Sanger sequencing method, so as to identify rare α or β thalassemia mutation.

Results: 1120 specimens were genotyped for thalassemia, out of them 547 thalassemia genes were determined. The detection rate was 48.8% (547/1120). 340 specimens were diagnosed as α thalassemia, and the detection rate was 30.6%, including 266 cases of -- SEA /αα, 44 cases of -α 3.7 /αα, 12 cases of -α 4.2 /αα, 8 cases of αα QS /αα,. 3 cases of Hb H disease ( 2 cases of -- SEA /-α 3.7 , 1 case of -- SEA /-α 4.2 ), 2 cases of αα CS /αα, 2 cases of αα WS /αα, 1 case of -α 3.7 /-α 3.7 , and 1 case of -α 3.7 /αα QS . Also, they contain 11 cases of rare α thalassemia, 8 kinds of rare types of α thalassemia mutations in combination, such as 4 cases of αα IVS-II-55 (T→G) in α1 /αα, 1 case of αα IVS-I-62 (C→T) in α1 /αα, 1 case of αα CD106（CTG→GTG）in α2 /αα, 1 case of αα HBA2:c.-24C>G /αα, 1 case of αα IVS-II-55 (T→G) in α1 /αα IVS-II-55 (T→G) in α1 , 1 case of αα IVS-II-55 (T→G) in α1 /αα IVS-II-119 (G;+CTCGGCCC) in α2 , 1 case of αα IVS-II-88 (G→A) in α2 /αα, and 1 case of -- THAI /αα. Among them, 5 α mutation sites were first reported, namely αα IVS-I-62 (C→T) in α1 , αα IVS-II-55 (T→G) in α1 , αα IVS-II-119 (G; +CTCGGCCC ) in α2 , αα IVS-II-88 (G→A) in α2 and αα CD106 (CTG→GTG) in α2 ; 2 α thalassemia mutation sites: αα HBA2: c.-24C>G and -- THAI were detected again in the Chinese population, respectively. 188 specimens were diagnosed as β thalassemia with a detection rate of 16.8%. Among them, 68 cases of β IVS-II-654 /βN, 47 cases of β CD41-42 /βN, 20 cases of β CD17 /βN, 17 cases of β -28 /βN, 7 cases of β CD27-28 /βN, 7 cases of βE/βN, 3 cases of β CD71-72 /βN and 2 cases of β CD43 /βN. And 17 cases were diagnosed as rare β thalassemia, 8 kinds of rare types were β thalassemia mutations in combination. There were 4 cases of β IVS-II-81 (C→T) /βN, 3 cases of β Hb J-Bangkok /βN, 3 cases of β Hb New York /βN, 2 cases of β -96 (G→T) /βN, 2 cases of β IVS-II-806 (G→C) /βN, 1 case of β Codons 8/9 /βN, 1 case of β Hb G-Coushatta /βN, 1 case of β IVS-II-827 (A→T) /βN. Among them, 3 β thalassemia mutation sites were reported for the first time, namely β -96 (G→T) , β IVS-II-806 (G→C) and β IVS-II-827 (A→T) ; it was found that in the Chinese population as β Codons 8/9 , β Hb G-Coushatta , β Hb J-Bangkok , β Hb New York , and β IVS-II-81 (C→T) , respectively. 19 cases were diagnosed as αβ-complex thalassemia, out of which 15 types of thalassemia mutation combinations were detected. They contain 2 cases of rare αβ-complex thalassemia, which are αα IVS-II-55 (T→G) /αα complex β IVS-II-81 (C→T) /βN, αα IVS-II-65 (G→A) in α1/αα complex β Hb G-Coushatta /βN.

Conclusion: The types of thalassemia gene mutations in Nanping area of Fujian province are genetically heterogeneous. The prevention and control strategies of thalassaemia in this area should be based on the prevention and treatment of common α thalassemia and β thalassaemia. And the attention should be paid to the types of rare and unknown gene mutations using screening and testing method.