ABSTRACT
Objective To study the molecular genetic mechanism of congenital central hypoventilation syndrome ( CCHS).Method The clinical data and molecular genetics results of CCHS diagnosed in neonatology department from 2014 to 2016 were analyzed retrospectively.The relationship between genotypes and clinical phenotypes in patients of CCHS was analyzed , and the diagnostic thinkings , follow－up and prognosis were summarized.Result A total of 4 infants with CCHS were included in this study.Among them, 2 were boys and the other 2 were girls.They were all full－term neonates without asphyxia at birth , but they soon sufferd from dyspnea and cyanosis , required assisted ventilation.One case had difficult defecation. All 4 cases had difficulty in weaning.The respiratory rhythm became weak developed apnea and carbon dioxide retention was detected in blood gas analysis.All the 4 cases died after withdrawal of treatment.The results of molecular genetic testing were as follows.There was a 38bp heterozygous deletion mutation in exon 3 of gene PHOX2B ( e.756＿776 del21bp).Three cases were found small fragment insertion in exon 3 of gene PHOX2B, which attributed to polyalanine repeat expansion mutations (PARMs).One case belonged to type 20/27 and another 2 cases belonged to type 20/26.Conclusion The main manifestation of CCHS in the neonatal period is ventilator dependant , which can combined with megacolon and atypical autonomic nerve disorder.According to the literature, more than 95%of CCHS are caused by the PHOX2B mutation. The symptom is severe when it got a non－PARMs mutation.It′s useful to make a definite diagnosis with genetic diagnosis results , which could be helpful for treating and predicting.Only effective respiratory support and standardized follow－up system can improve the quality of life in patients of CCHS.
ABSTRACT
OBJECTIVE@#To explore the genetic basis for a neonate featuring hyperammonemia.@*METHODS@#The patient was examined and tested by tandem mass spectrometry and next generation sequencing (NGS). Suspected mutations were confirmed by Sanger sequencing of the proband and her parents. Potential impact of the mutation was predicted with SIFT, PolyPhen-2 and MutationTaste software.@*RESULTS@#Plasma ammonia and alanine were significantly increased in the proband, while serum citrulline was decreased. The neonate was found to harbor compound heterozygous mutations of the CPS1 gene [c.1631C>T(p.T544M) and c.1981G>T(p.G661C)], which were respectively inherited from her father and mother.@*CONCLUSION@#The carbamoyl phosphate synthetase I deficiency of the proband can probably be attributed to the mutations of the CPS1 gene. Above finding has expanded the spectrum of CPS1 mutations in association with carbamoyl phosphate synthetase I deficiency.