Objective:To summarize the clinical features, gene mutations and experience of standardized enzyme replacement therapy (ERT) of Pompe disease (PD) in children.Methods:A retrospective analysis was performed on the clinical data of 13 children with PD, who were hospitalized in Qingdao Women and Children′s Hospital from December 2016 to August 2021.According to the age at onset, the children were divided into the infantile-onset Pompe disease (IOPD) group and late-onset Pompe disease (LOPD) group.At the same time, they were divided into the ERT group and non-ERT group according to whether recombinant human acid alpha-glucosidase (rhGAA) was infused.Furthermore, the ERT group was divided into the standard ERT group and non-standard ERT group.The standard ERT group received a dose of 20 mg/kg every 2 weeks for 52 weeks.The survival rate was compared between groups by using the Kaplan-Meier method.Results:Among the 13 children with PD, there were 7 males and 6 females.Ten cases belonged to the IOPD group and 3 cases belonged to the LOPD group.The most common cause of initial consultation in the IOPD group was cardiac involvement, which accounted for 60.0% (6/10 cases), while the LOPD group mainly presented with myasthenia, cardiac involvement and respiratory tract infection at the first diagnosis.The serum level of creatine kinase (CK) in all cases increased to varying degrees.Acid alpha-glucosidase (GAA) was completely deficient in 1 case and decreased in 12 cases.All the children in the IOPD group showed myocardial hypertrophy, electrocardiograph (ECG) suggested a short PR interval, increased QRS voltage and extensive T-wave inversion.Three new mutations were found by GAA gene analysis, and they were c. 1861T>G (p.Trp621Gly), c.2278A>T (p.K760X), and c. 949G>A (p.A317T). Five cases in the IOPD group were given ERT.Two of them were given standard ERT for 52 weeks, and the other 3 cases were treated with non-standard ERT.At the end of follow-up, 2 cases treated with standardized ERT survived and the remaining 8 cases died of heart failure or respiratory failure.In the LOPD group, only 1 case was given ERT one time.Finally, 2 cases survived and one died of respiratory failure.The total fatality rate was 69.2%(9/13 cases). The survival rate of the ERT group (50.0%) and standard ERT group (100.0%) was significantly higher than that of the non-ERT group (14.3%) ( Log Rank P=0.037, 0.044). Conclusions:The clinical manifestations of PD are diverse.GAA activity examination and GAA gene analysis are important for clinical diagnosis of PD.Standardized ERT can significantly delay the progression of PD and even reverse myocardial hypertrophy in children with IOPD.

Objective:To investigate the short-term and medium-term changes of the left ventricular ejection fraction (LVEF) and the predictive value of relevant electrocardiogram (ECG) indexes in children with dilated cardiomyopathy (DCM) complicated with complete left bundle branch block (CLBBB).Methods:Children clinically diagnosed with DCM in the Department of Heart Center, Women and Children′s Hospital, Qingdao University and Beijing Anzhen Hospital, Capital Medical University between November 2011 and August 2020 were retrospectively recruited.According to the combination of CLBBB, they were divided into CLBBB group and non-CLBBB group.Echocardiogram and ECG were regularly performed.Short-term and medium-term changes of LVEF based on the 1-5-year follow-up data were compared between groups.COX proportional hazards model and Kaplan-Meier multiplicative limit method were used to analyze the predictive value of ECG indexes of LVEF changes in children with DCM combined with CLBBB.Results:Ninety-four children with DCM were enrolled, including 35 cases in CLBBB group and 59 cases in non-CLBBB group.There was no difference in baseline LVEF between groups.However, significant differences were found in QRS duration, corre-cted QT interval(QTc), R peak time in lead V 5 (T V5R) and QRS notching or slurring between groups ( P<0.05). LVEF of all children showed an upward trend within one year after onset, while the Z value of eft ventricular end diastolic diameter(LVEDd) showed a downward trend, and the two indexes tended to be stable within 1 - 5 years.The Z value of LVEDd in CLBBB group was significantly higher than that of non-CLBBB group, while LVEF was significantly lower (all P<0.05). The mean LVEF of CLBBB group slightly fluctuated around 50%, that of LVEF in non-CLBBB group was 60%.The multivariate COX regression analysis showed that QRS duration ( HR=0.979; 95% CI: 0.960-0.999, P<0.05) and QTc ( HR=0.988; 95% CI: 0.979-0.998, P<0.05) were independent predictors of LVEF recovery in children with DCM.Kaplan-Meier method showed a significant difference of LVEF normalization between DCM children with different QRS durations ( P<0.05), which was also detected in those with QTc interval ( P<0.05). Conclusions:LVEF of children with DCM combined with CLBBB increases in the short term after standard treatment, and then being stable.CLBBB can affect the recovery of left ventricular systolic function in children with DCM.Moreover, QRS duration and QTc interval are independent predictors of LVEF recovery in DCM children.