30 417例儿童地中海贫血基因类型分析

Genotypes of thalassemia in children: an analysis of 30 417 cases

摘要:

目的 了解广西地区儿童地中海贫血基因类型及其分布。 方法 2011年1月至2019年12月对广西壮族自治区妇幼保健院30 417例地中海贫血筛查阳性患儿采用单管多重PCR后经琼脂糖凝胶电泳和反向点杂交技术进行常见α、β地中海贫血基因检测。对2 703例疑似罕见地中海贫血患儿进行跨越断裂点PCR检测和/或基因序列分析。 结果 30 417例地中海贫血筛查阳性患儿中，确诊地中海贫血23 214例（76.32%），其中α、β及α合并β地中海贫血检出率分别为47.77%、23.75%和4.80%。检出13种α地中海贫血等位基因共计18 480个，以--^SEA为主（54.98%），包括7种罕见等位基因：--^THAI（0.43%）、HKαα（0.02%）、-α³⁰（0.01%）、-α^1.0（0.01%）、-α^2.4（0.01%）、-α^21.9（0.01%）和HBA₂:C272-279 del（0.01%）；检出17种β地中海贫血等位基因共计9 168个，主要为CD41-42（47.79%），其次是CD17（25.53%），包括3种罕见等位基因：IVS-Ⅱ-5（0.02%）、IVS-I-2（0.01%）和^Gγ(^Aγδβ)⁰（0.01%）。14 531例α地中海贫血患儿中检出37种基因类型，6种主要类型为--^SEA/αα（52.20%）、-α^3.7/αα（13.24%）、α^CSα/αα（7.52%）、-α^4.2/αα（6.06%）、--^SEA/-α^3.7（5.91%）和α^WSα/αα（3.41%），共占88.34%。7 223例β地中海贫血患儿中检出49种基因类型，6种主要类型为CD41-42/β^N（45.81%）、CD17/β^N（24.30%）、IVS-Ⅱ-654/β^N（7.49%）、-28/β^N（5.62%）、CD71-72/β^N（4.42%）和CD26/β^N（3.94%），共占91.13%。1 460例α合并β地中海贫血患儿中检出137种基因类型，主要为--^SEA/αα合并CD41-42/β^N（14.17%）、CD17/β^N（8.35%）。HbH病（α⁰/α⁺）2 050例，包括合并β地中海贫血杂合子134例；巴氏水肿胎（--^SEA/--^SEA）12例；β地中海贫双重杂合子355例、纯合子128例，包括合并α地中海贫血93例。 结论 广西地区儿童地中海贫血基因突变多样，基因类型丰富；以α地中海贫血为主，--^SEA/αα是主要基因类型；α合并β地中海贫血比例较高，β地中海贫血双重杂合子和纯合子（中重型）患儿出生较多。

Abstract:

Objective To investigate the distribution of genotypes of thalassemia in children in Guangxi, China. Methods A total of 30 417 children with positive results of thalassemia screening in the Maternal and Child Health Hospital of Guangxi Zhuang Autonomous Region from January 2011 to December 2019 were enrolled. Single-tube multiplex PCR, agarose gel electrophoresis, and reverse dot blot hybridization technique were used for the detection of common α- and β-thalassemia genes. Gap-PCR or gene sequence analysis was performed for 2 703 children suspected of rare thalassemia. Results Among the 30 417 children with positive results of thalassemia screening, 23 214 (76.32%) were diagnosed with thalassemia, and the detection rates of α-thalassemia, β-thalassemia, and α-thalassemia with β-thalassemia were 47.77%, 23.75%, and 4.80% respectively. A total of 13 types of α-thalassemia alleles (18 480 alleles in total) were detected, mainly --SEA (54.98%), including seven rare alleles, i.e., --THAI (0.43%), HKαα (0.02%), -α30 (0.01%), -α1.0 (0.01%), -α2.4 (0.01%), -α21.9 (0.01%), and HBA2:C272-279 del (0.01%). A total of 17 types of β-thalassemia alleles (9 168 alleles in total) were detected, mainly CD41-42 (47.79%), followed by CD17 (25.53%), including three rare alleles, i.e., IVS-II-5 (0.02%), IVS-I-2 (0.01%), and Gγ(Aγδβ)0 (0.01%). A total of 37 genotypes were detected in 14 531 children with α-thalassemia, among which the most common 6 genotypes were --SEA/αα (52.20%), -α3.7/αα (13.24%), αCSα/αα (7.52%), -α4.2 (6.06%), --SEA/-α3.7 (5.91%), and αWSα/αα (3.41%), accounting for 88.34%. A total of 49 genotypes were detected in 7 223 children with β-thalassemia, among which the most common 6 genotypes were CD41-42/βN (45.81%), CD17/βN (24.30%), IVS-II-654/βN (7.49%), -28/βN (5.62%), CD71-72/βN (4.42%), and CD26/βN (3.94%), accounting for 91.13%. A total of 137 genotypes were detected in 1 460 children with both α- and β-thalassemia, mainly --SEA/αα combined with CD41-42/βN (14.17%) and CD17/βN (8.35%). A total of 2 050 children were diagnosed with hemoglobin H disease (α0/α+), among whom 134 had β-thalassemia heterozygote and 12 had Bart hydrops fetalis syndrome (--SEA/--SEA); 355 children were diagnosed with β-thalassemia double heterozygote, and 128 were diagnosed with β-thalassemia homozygote, including 93 children with α-thalassemia. Conclusions There are diverse gene mutations and rich genotypes of thalassemia among children in Guangxi, and α-thalassemia is more common, with --SEA/αα as the major genotype. There is a high proportion of children with both α- and β-thalassemia, and there are relatively high incidence rates of β-thalassemia double heterozygote and homozygote (intermedia and major).