| Objectives: To verify whether SP-C gene mutations are the pathogenic factors of neonatal respiratory distress syndrome(NRDS) in Han population and broaden the horizon of clinical diagnosis and treatment of NRDS, we analysed the structure of SP-C gene of exonⅠto Ⅲ, screened SP-C gene mutation types and evaluated genetype and gene frequency of SP-C mutations to investigate the relationship between SP-C gene mutations and the morbidity and severity of NRDS. Methods: From January 2013 to December 2014 in neonatal intensive care unit of Ba Yi Children’s Hospital Affiliated to the General Military Hospital of Beijing PLA, a total of 90 cases with NRDS was selected as NRDS group, a total of 90 cases were grouped into three subgroups of 30 cases each: neonates born at gestational age(GA) <32weeks, 32weeks≤GA<37weeks and GA≥37weeks respectively. Clinical data, in which including gender,gestational age, birth weight(BW),mode of delivery, asphyxia, premature rupture of membrane, abnormal placenta, prenatal situation of mother, blood rutine, arterial blood gas analysis, blood culture, sputum culture, chest x-ray, mechanical ventilatory support, surfactant used and outcome, were collected with observing table. A total of 90 cases without RDS as control group were matched with NRDS group according to the GA, gender and BW,cases in control group might suffer from necrotizing enterocolitis, congenital intestinal atretia and congenital abdominal diseases.Whole-blood samples were collected into plastic EDTA tubes. Genomic DNA was extracted with routine technique. The analysis of SP-C gene mutation, in which included those in exonⅠ、Ⅱ、Ⅲ, was performed with polymerase chain reaction(PCR) and gene sequencing. Differences of allele frequencies(invariant allele and variant allele) and genotype frequencies(invariant genotype and variant genotype) between NRDS group and control group were analyzed. The Hardy-Weinberg equilibrium was used for ensuring the representation of subject investigated. The gestational age and birth weight between the two groups were compared with Independent-Samples T Test. The composition of gender,mode of delivery, outcome and the differences of allele or genotype frequencies between the two groups were compared with Chi-square Test. Results:(1) Heterozygous missense mutations including c.115G>T and c.139G>C existed in exon Ⅱ of SP-C gene. Two missense mutations above only were discovered in NRDS group and changed amino acid sequence of SP-C protein. Meanwhile, the heterozygous synonymous mutation of c.228G>C existed in exon Ⅲ. The mutation above was discovered in two groups and didn’t changed amino acid sequence of SP-C protein. The three heterozygous mutations above had not been reported before. No mutation was found in exonⅠof SP-C gene.(2) The heterozygous missense mutation(c.115G>T) in NRDS group had two genotypes: GG(wild type) and G/T(mutant type). The genotype frequency of mutant type(G/T) in NRDS was 0.078 while the gene frequency of mutant type(T) was 0.039. The genotype frequency(0.078) of mutant type(G/T) was higher than that(0) in control group(2x =7.283, p <0.05)while the gene frequency(0.039) of mutant type(T) was higher than that(0) in control group(2x =7.139, p <0.05). Among NRDS group:The genotype frequency(1.000) of G/T in 55 cases with III-IV grade chest change was higher than that(0.578) of GG(2x =4.830, p <0.05),the frequency of T allete(1.000) was higher than that of G allete(0.595)(2x =4.635, p <0.05).The genotype frequency(0.571) of G/T in 7 cases of death was higher than that(0.036) of GG(2x =25.788, p <0.01),the frequency of T allete(0.571) was higher than that of G allete(0.058)(2x =24.744, p <0.01).(3)The heterozygous missense mutation(c.139G>C) in NRDS group had two genotypes: GG(wild type) and G/C(mutant type). The genotype frequency of mutant type(G/C) in NRDS was 0.067 while the gene frequency of mutant type(C) was 0.033. The genotype frequency(0.067) of mutant type(G/C) was higher than that(0) in control group(2x =6.207, p <0.05) while the gene frequency(0.033) of mutant type(C) was was higher than that(0) in control group(2x =6.102, p <0.05). Among NRDS group:The genotype frequency(0.167) of G/C in 64 cases with cesarean section was lower than that of GG(0.750)(2x =9.276, p <0.01)while the frequency of C allete(0.167) was lower than that of G allete(0.730)(2x =8.956, p <0.01).The genotype frequency(0.167) of G/C in 55 cases used three or four doses PS was lower than that(0.643) of GG(2x =5.343, p <0.05) while the frequency of T allete(0.167) was higher than that of G allete(0.626)(2x =5.159, p <0.05).(4)The heterozygous silent mutation of c.228G>C in NRDS group and control group had two genotypes: GG(wild type) and G/C(mutant type). The genotype frequency of mutant type(G/C) in NRDS was 0.089 while the gene frequency of mutant type(C) was 0.044. The genotype frequency(0.089) of mutant type(G/C) was higher than that(0.011) in control group(2x =5.731, p <0.05), meanwhile, the gene frequency(0.044) of mutant type(C) was was higher than that(0.006) in control group(2x =5.584, p <0.05).There is no associatation between c.228G>C and clinical indicators studied in NRDS( p >0.05). Conclusions:Our results suggest following conclusions:First,three heterozygous mutations locate in SP-C gene of exonⅡtoⅢin Chinese Han population of this study, these mutations including c.115G>T,c.139G>C and c.228G>C have never been reported before. Second,c.115G>T of SP-C gene mutation is associated with pathogenesis and severity of NRDS and increases the risk of death in NRDS. Third, c.139G>C of SP-C gene mutation is associated with pathogenesis of NRDS, but it dosen’t increase the risk of severity and death in NRDS. The fourth, c.228G>C of SP-C gene mutation is associated with pathogenesis of NRDS. There is no associatation between c.228G>C and clinical indicators studied in NRDS. |
PDF Full Text Request