Analysis of haematological phenotype and mutation spectrum of δ-globin gene from Guangdong area in Chinese Han prenatal population

Abstract

Objective: To analyze the genotype-phenotype correlations among southern Chinese Han prenatal population in Guangdong area with δ-globin gene mutation, so as to enrich the delta-thalassemia gene mutations data. Methods: A total of 33 cases were selected in 7 580 patients during prenatal thalassemia trait screening, from January 2012 to May 2015(including 10 males and 23 females, aged 22-48 years old). Complete blood cell count was performed on a XE 4000i automatic hemocyte analyzer. Hb, HbF and HbA2 were tested by high performance liquid chromatography (HPLC). Genomic DNA was extracted from whole blood samples using a whole blood genomic DNA extraction kit. Polymerase chain reaction (PCR) was used to amplify three different fragments corresponding to the exons and the regulatory sequences using three different couples of primers for the δ-globin gene. Results: Twenty one of the 33 samples were positive for the δ-globin gene defects. Four previously known mutations were detected: including 12 cases for -77(T>C)[HBD c. -127 (T>C)](57.14%), 4 cases for -30 (T>C)[HBD c. -80 (T>C)](19.05%), 1 case for codon 10 (-G) (HBD c. 31delG)(4.76%), and 1 case for HBD c. 244 C>T(4.76%). Three new δ-globin gene defects which had not yet been reported in database were detected, including 1 case for HBD c. 22_24delGAG(4.76%), 1 case for HBD c. 347 C>T(4.76%), and one case for HBD c. 349 C>G(4.76%). Conclusions: -77 (T>C) is the most common mutation in Chinese southern prenatal population. Three new HBD gene mutations are referred in this report, which provide the valuable information for genetic counseling and prenatal diagnosis in Guangdong area.