Molecular diagnosis of thalassemia compound heterozygotes in PUMCH from 2012 to 2015

Abstract

Objective To investigate the genotype distribution of thalassemia intermedia, major and compound thalassemia in Peking Union Medical College Hospital from 2012 to 2015. Methods Retrospectively 1 084 suspected thalassemia cases were analyzed in recent four years. Three common deletions of α globin chain were detected by GAP-PCR. Three common point mutations of α globin chain and seventeen common mutations of β globin chain were identified by PCR reverse dot blot hybridization. Hemoglobin electrophoresis was carried out by Capillary Electrophoresis System. RBC associated parameters and morphology were analyzed by hematology analyzer and blood smear. Results 702 cases were confirmed to be thalassemia, and the positive rate was 64.76% (702/1084). 19 types of gene defects were detected. There were 4 types of gene defects in 23 case with α-thalassemia intermeida, including -α3.7/--SEA, -α4.2/--SEA, αCSα/--SEA and αQSα/--SEA, -α3.7/--SEA to be the most common genotype (18 cases) .3 cases with β-thalassemia intermeida were confirmed and the genotypes were βCD17(A→T)/β-29(A→G), β-28(A→G)/β-28(A→G) and βIVS-Ⅱ-654(C→T)/βCD17(A→T), respectively. There were also 1 βCD41-42(-TTCT)/βCD17(A→T) thalassemia major case. The genotypes of 2 HbE/β-thalassemia cases were βCD41-42(-TTCT)/βE and βCD17(A→T)/βE. 5 αβ-thalassemia including 2 βCD41-42(-TTCT)/βA compounded with αα/-α3.7, 1βIVS-Ⅱ-654(C→T)/βA compounded with --SEA/αCSα, 1βCD17(A→T)/βA compounded with -α4.2/αα and 1βCD41-42(-TTCT)/βA compounded with αCSα/αα. Rare and untypical haematological results were found, such as normal level HbA2 and undetectable HbH, in compound heterozygosity with --SEA/αCSα and βIVS-Ⅱ-654(C→T)/βA. Conclusions The genotypes of thalassemia intermedia, major and compound thalassemia in Peking Union Medical College were highly variable.(Chin J Lab Med, 2016, 39: 491-495) Key words: Thalassemia; alpha-globin; Beta-globin; Genotype; Hemoglobinometry