新生儿呼吸窘迫综合征ABCA3基因遗传缺陷的研究

目的 分析ATP结合盒式蛋白转运子亚单位基因ABCA3遗传缺陷与新生儿呼吸窘迫综合征(NRDS)的关系,从中探讨汉族人群NRDS发病的遗传机制.方法 收集在新生儿重症监护病房住院的11例重症NRDS患儿的临床资料,采集患儿和97例无关正常对照的血样,采用PCR扩增、DNA直接测序技术对11例患儿进行ABCA3基因序列分析,对于新发现的ABCA3错义突变在97例健康对照中进行单链构象多态性检测.对1例生后13 h死亡的NRDS患儿进行肺组织光镜和电镜检测.结果 在11例患儿中发现了3个ABCA3基因外显子遗传变异、1个剪切位点碱基变异和几个国外报道及尚未报道的ABCA3单核苷酸多态性(SNP).3个ABCA3基因外显子遗传变异分别为c.2169 G＞A (p.M723I)、c.1010 T＞G (p.V337G)、c.4972 A＞G(p.S1658G),1个剪切位点变异为Exon 30+2 T/G,发现的SNP位点包括未报道过的213 C ＞T(p.F71F)、Exon 21+ 34C/T和已报道的c.1059C＞T(p.F353F)等.1例生后12 h死亡的患儿携带c.2169G＞A纯合变异,该变异位于第17号外显子,碱基的变异导致第723位氨基酸由异亮氨酸代替蛋氨酸,97例健康对照者中未发现此变异.肺组织电镜检测显示该例肺泡Ⅱ型上皮细胞的板层小体变小、浓缩,电子致密物边集.结论 ABCA3基因突变可能是部分临床不能解释的重症NRDS患儿的遗传学病因或遗传背景,识别NRDS患儿ABCA3基因变异情况,有助于治疗措施的选择及评价,并为开展NRDS遗传咨询和早期预防性干预提供依据.

Detection of genetic defect within ABCA3 from newborns with respiratory distress syndrome

Objective To detect possible relationship between genetic defect within the gene encoding member A3 of the ATP Binding Cassette family (ABCA3) and neonatal respiratory distress syndrome (NRDS),thus to understand the genetic mechanisms of NRDS in Han ethnic group.Method The clinical data of 11 cases with NRDS hospitalized in neonatal intensive care unit was investigated.Blood samples were collected from 11 cases with NRDS and 97 unassociated normal individuals.Polymerase chain reaction (PCR) and DNA direct sequencing were performed to screen all exons and their flanking introns of ABCA3 gene for mutation analysis in 11 cases with NRDS.If a new missense variation was identified,single strand conformation polymorphism analysis was performed in 97 healthy controls.Lung tissue sample from a case who died 12 hours after birth was examined with light microscopy and electron microscopy. Result Three missense genetic variants in exons,which include c.2169 G ＞ A ( p.M723I),c. 1010 T ＞ G (p.V337G),c.4972 A ＞ G (p.S1658G),one splice junction site variation (Exon 30 +2 T/G),several unreported polymorphism sites [213 C ＞ T(p.F71F),exon 21 + 34C/T] and reported polymorphism site (p.F353F) were identified on ABCA3 gene coding region in 11 caes.The homozygous variation (c.2169G ＞A),which was in exon 17 and causes an M723I amino acid change,was found in the case who died 13hours after birth,but not detected in 97 controls,indicating that this variation is indeed a mutation and not a polymorphism.In the case carrying c.2169G ＞ A,ultrastructural examination of the alveolar type Ⅱ cells with electron microscopy demonstrated abnormally small and dense lamellar body with eccentrically distributed electron dense substance.Conclusion Genetic variants within ABCA3 may be the genetic cause of or a contributor to some unexplained refractory NRDS.Identification of ABCA3 genetic variant in NRDS infants is important to establish appropriate management and evaluation of treatment options,as well as to offer genetic counseling and prenatal diagnosis.