Objective:To investigate the pathogenesis, precaution and treatment of neonatal congenital complete heart block (CCHB) in twins.Methods:The clinical data of a case of premature twins with neonatal CCHB from the Department of Neonatology, the First Affiliated Hospital of Xinxiang Medical University were retrospectively analyzed and related literature was reviewed.Results:(1)Case review: the 37-year-old gravida had no symptoms.Fetal ultrasound cardiogram(fUCG)at 23 weeks of gestation indicated bradycardia and CCHB.Then, the mother was diagnosed with undifferentiated connective tissue disease.After treatment with human immunoglobulin, dexamethasone and hydroxychloroquine, fUCG at 31 weeks of gestation still suggested CCHB.An emergency cesarean section was performed on the diagnosis of threatened preterm labor.With weakly positive neonatal antinuclear antibody (ANA), and positive Ro60 and Ro52 autoantibodies, twins were diagnosed with CCHB by 24 hour-Holter monitors.One of the twins was discharged with CCHB (ventricular rate of 80-90 times/min) after systemic therapy, but the weight increased to 2 200 g. The other one of the twins suffered from the sudden decrease of heart rate and blood pressure and finally died of sudden cardiac arrest.(2) Literature search: two cases in Chinese and 9 cases in English were reviewed.Among them, 9 cases were sjogren syndrome type A (SSA)/Ro and sjogren syndrome type B(SSB)/La related CCHB, and 2 cases were idiopathic CCHB.Conclusions:The placental transfer of anti-SSA or anti-SSB is an important mechanism of neonatal CCHB in twins, and other factors may also be involved.Current treatments are unsatisfactory.Most patients need pacemaker implantation.Early diagnosis and prenatal management can improve the prognosis.

Objective:To study the clinical manifestations and genetic characteristics of neonatal-onset primary mitochondrial disease (PMD) caused by nuclear gene mutations.Methods:From May 2020 to March 2022, the clinical data, genetic results and follow-up information of neonates with PMD admitted to the Department of Neonatology of our two hospitals were retrospectively analyzed.Results:A total of 4 patients were enrolled, all with hyperlactatemia and metabolic acidosis. In case 1, the fetal cranial MRI showed agenesis of corpus callosum. In case 2, echocardiography after birth indicated hypertrophic cardiomyopathy. Whole exome sequencing found the following mutations: EARS2 nuclear gene c.1294C>T and c.971G>T variants, COA6 nuclear gene c.411_412insAAAG variant, ACAD9 nuclear gene c.1278+1G>A and c.895A>T variants, FOXRED1 nuclear gene c.1054C>T and c.3dup variants. Mitochondrial second-generation sequencing and multiplex ligation-dependent probe amplification showed no abnormalities. Cases 1 and 3 died during the neonatal period. Case 2 died at 2-year-and-2-month of age. Case 4 was followed up to 1 year of age with developmental delay.Conclusions:The main phenotypes of neonatal-onset PMD caused by nuclear gene mutations are hyperlactatemia, refractory metabolic acidosis and cardiomyopathy, which have a poor prognosis. Proactive genetic tests are helpful for early diagnosis.