Feeding difficulty is the dominant feature in 12 Chinese newborns with CHD7 pathogenic variants

Monodactyly in a patient with CHARGE syndrome: An additional case report

CHARGE syndrome is a rare autosomal dominant syndrome characterized by multiple congenital anomalies including coloboma, heart defects, ear anomalies, and developmental delay, caused by pathogenic variants in the CHD7 gene. The discovery of the molecular basis of this syndrome increased the number of cases reported and expanded the phenotype and clinical variability. Limb anomalies are occasional clinical findings in this syndrome, present in about 30% of reported cases. The occurrence of limb anomalies in this syndrome suggests that it should be considered as part of the phenotypic spectrum. Here, we describe an individual with CHARGE syndrome presenting unilateral monodactyly.

Generation and characterization of Chd7-iCreERT2-tdTomato mice

Heterozygous mutation of CHD7 gene causes a severe developmental disorder called CHARGE syndrome. In order to further explore the expression and function of Chd7 in vivo, we generated a Chd7-P2A-iCreERT2-P2A-tdTomato (in short, Chd7-CT-tdT) knockin mouse line using the CRISPR/Cas9 technology. The specificity and efficiency of two knockin genetic elements were validated. The Chd7-CT-tdT reporter gene could accurately reflect both the dynamic expression pattern of endogenous Chd7 during neurodevelopment and cell-type specific expression in the brain and eye. The recombination efficiency of Chd7-CT-tdT in postnatal cerebellum is very high. Moreover, lineage tracing experiment showed that Chd7 is expressed in intestinal stem cells. In summary, the newly constructed Chd7-CT-tdT mouse line provide a useful tool to study the function of Chd7.

Deletion of the chd7 Hinders Oligodendrocyte Progenitor Cell Development and Myelination in Zebrafish

CHD7, an encoding ATP-dependent chromodomain helicase DNA-binding protein 7, has been identified as the causative gene involved in CHARGE syndrome (Coloboma of the eye, Heart defects, Atresia choanae, Retardation of growth and/or development, Genital abnormalities and Ear abnormalities). Although studies in rodent models have expanded our understanding of CHD7, its role in oligodendrocyte (OL) differentiation and myelination in zebrafish is still unclear. In this study, we generated a chd7-knockout strain with CRISPR/Cas9 in zebrafish. We observed that knockout (KO) of chd7 intensely impeded the oligodendrocyte progenitor cells' (OPCs) migration and myelin formation due to massive expression of chd7 in oilg2+ cells, which might provoke upregulation of the MAPK signal pathway. Thus, our study demonstrates that chd7 is critical to oligodendrocyte migration and myelination during early development in zebrafish and describes a mechanism potentially associated with CHARGE syndrome.

Phenotypic spectrum of typical CHARGE syndrome in a Chinese male neonate: a case report

CHARGE syndrome is a rare and complex disorder, causing multiple birth defects and sensory deficits. The CHD7 gene was proved to be the major pathogenic gene in CHARGE syndrome. To date, the phenotype of neonatal CHARGE syndrome is still poorly recognized. In this paper, we report a Chinese neonate with typical CHARGE syndrome. During his stay in the neonatal intensive care unit of our hospital, the patient presented with various appearance abnormalities, severe dyspnea, dysphagia and recurrent infection. Integrated analysis of the clinical manifestations and examinations suggested a diagnosis of CHARGE syndrome. Later, the genetic analysis revealed a de novo null heterozygous pathogenic mutation in the patient's CHD7 gene [c.6292C>T (p.Arg2098*)]. Taken together, the patient was diagnostic confirmed as typical CHARGE syndrome. The physicians provided symptomatic treatments for the patient which significantly alleviated his condition, including infection control, laryngoplasty, nasogastric tube feeding and respiratory support. To our knowledge, this case broadens the clinical phenotypic spectrum of typical CHARGE syndrome in neonatal period due to the null mutation of CHD7 gene [c.6292C>T (p.Arg2098*)]. It also demonstrates that genetic analysis is essential in the diagnosis of CHARGE syndrome early in life. Clinicians should focus on providing supportive and corrective therapies in early treatment, particularly in controlling infection, and improving breathing and feeding.